Using WordPress ‘has_site_icon()’ PHP function
The `has_site_icon()` function in WordPress returns true if the site has a Site Icon set, otherwise false
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Using WordPress ‘has_nav_menu()’ PHP function
Determines whether a registered nav menu location has a menu assigned to it.
Using WordPress ‘has_filter()’ PHP function
Checks if any filter has been registered for a hook.
Using WordPress ‘has_category()’ PHP function
Checks if the current post has any of given category.