how to modify request to get_template_part()?

Just looked in the P2 theme files. The theme loads the entry.php with the function p2_load_entry() located in inc/template-tags.php.

If you want to edit the entry.php file and want to be on the safe side if P2 releases an update, you should create a Child Theme.

  1. Create a new sub-folder inside wp-content/themes/ e.g. p2-child
  2. Inside the new folder, create a style.css with the content described in the above linked article. Be sure that you have added Template: p2 to the comment block.
  3. Copy entry.php to the new folder and edit it.
  4. Go to WordPress Admin Appearance > Themes and activate your newly created P2 Child Theme.