how to wrap tag in tag html to wordpress menu conversion

You’ll want to use the link_before and link_after arguments for the wp_nav_menu. Setting them to '<span>' and '</span>' respectively.

wp_nav_menu( [
  'menu_class'     => 'menu menu-main',
  'container'      => '',
  'theme_location' => 'main_menu',
  'link_before'    => '<span>',
  'link_after'     => '</span>'
] );