If (category / tag checked) then (display header2php)

You can use the has_category() function for this:

if ( has_category( 'Grizzly Bears' ) ) {
  get_header( 'header2' );
} else if ( has_category( 'Peace Pipes' ) ) {
  get_header( 'header3' );
}

You can add the has_tag function as well. Both accept an array of term IDs, names or slugs if you want to check multiples at once.

Edit: changed in_category to has_category for consistency and potential future deprecation

Related Posts:

  1. What is the condition to check if we are in admin or frontend?
  2. if (is_page(**PAGE ID**)) not working
  3. is_home , is_front_page not working
  4. What is the correct method for determining ‘is_front_page’ when using filters such as ‘pre_get_posts’ and ‘posts_where’?
  5. how to check if front page is set to show a static page
  6. Way to check if we are in Theme Customizer mode? [duplicate]
  7. How can we use conditional tags in plugins?
  8. Possible to use conditionals within add_feed() callback?
  9. is_home() vs is_archive()
  10. Blog Posts vs Static Page (conditional statements)
  11. Adding Controls to Theme Customizer If Certain Page Template is Active
  12. Problem with “conditional tag”: if empty
  13. Do I need to include ‘else’ and/or ‘endif’?
  14. is_singular() equivalent for backend
  15. Make specific tag visible only to logged in users in front-end
  16. How can i know when i can execute what functions of wordpress?
  17. Issue getting gettext to work with conditional statements
  18. Post tags show outside loop?
  19. Need help with else if statement
  20. WordPress conditionals not working
  21. Cannot Use is_single() and is_admin in functions.php
  22. Hide a template part when page is password protected?
  23. Limit Contact Form 7 hook to specific form [closed]
  24. Checking whether template part is loaded in a page
  25. Conditional tags inside a class
  26. Use slug rather than id for $post->post_parent?
  27. Identify a Woocommerce page by WordPress conditional tags
  28. is_page conditional question
  29. Trouble with parent and child conditional tag to show content
  30. A simple method for disabling WPML language switcher when meeting specific circumstances [closed]
  31. Display a div only in some author’s single posts
  32. What do I add to this code to include additional CPTs?
  33. Loading template parts conditionally in Customizer
  34. Conditional check for embedded video in the_content
  35. Conditional IF statement not returning true even though echo of $user->province is correct
  36. is singular and is home not working
  37. add styles if custom header was included
  38. Check if user registered more than a month ago
  39. If page displays posts conditional
  40. Conditional tags not working
  41. How to check with is_page if 404.php is loaded?
  42. I need use is_single in functions.php
  43. How to apply a function if conditon a & b [closed]
  44. Conditional display faults
  45. Conditionals: What is wrong with my if/else statements? [closed]
  46. Only on single post page
  47. is_home() returns true while it shouldn’t
  48. Conditional tags help (if none, don’t display anything)
  49. How to display a feature only if custom field value is set?
  50. Filter for the Custom Post List Page
  51. Additional conditions tags to work
  52. Can this code be concatenated?
  53. Conditional: current user updated post in the last X days
  54. How can I get $pagenow equals to the Home Page or specific page on my site?
  55. page single conditional
  56. Three variables on conditional tags
  57. Is it possible to If statement “article already appears on page”?
  58. How to use the conditional homepage tag
  59. Which is the right order of the conditional tags on pages?
  60. Hide breadcrumbs on specific pages
  61. Pre Get Posts – Difference between conditional() and $query->conditional()?
  62. If less than IE9 [closed]
  63. Cannot retrieve active members only
  64. Else statement not triggering after a failed if statement
  65. Custom Function for Portfolio Archive Template With Conditonal Tag
  66. Conditional Custom Image Header
  67. Trying to place shortcode/css/html into an IF conditional statement
  68. Conditional Tag Based on Age of Post [duplicate]
  69. Will multiple conditionals slow down page load?
  70. Conditional single.php statement not recognizing conditionals
  71. Conditional tag-like function to tell if post is in trash?
  72. Conditional Tags and Echo HTML / divs or CSS and Display: none?
  73. Getting false for is_home() on Posts page
  74. Get value in TCPDF
  75. Content visibility condition based on date
  76. How to target a search result page?
  77. Why is_page() returns false when visiting the static page declared as “posts page”
  78. if is NOT custom post type OR is NOT page combination [closed]
  79. What changes are needed for this conditional code to work on deeper levels?
  80. How to detect if bbPress forum index
  81. Conditional tags returning different results for different areas on a page?
  82. WordPress Conditionals Giving Me A Headache
  83. PHP inside echo HTML?
  84. Conditional statements in wordpress themes
  85. My Conditional Tags not Working
  86. Hide page header on both index and author pages [closed]
  87. How to check if the current page’s parent is one of 2 different ID’s
  88. Showing code only on Front Page “Posts Page”
  89. Run a php function if a predefined page is visited
  90. nested conditional to check for feature image and custom field?
  91. Display Latest Post on a Page Conditionally
  92. is_archive for custom tax archive page?
  93. Help with adding conditional title tags to header.php
  94. Custom Headers on Blog Posts Page
  95. Conditional statement with three condition
  96. if is_page(‘slug’)
  97. How do I combine these two conditionals? [closed]
  98. problem with not displaying content on selected pages
  99. hide block of code from showing on certain pages
  100. Quick Conditional Tag Question if elseif [closed]
Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)