Switch From Classic to Transitional

The difference is that in Transitional mode you’ll be able to use the exact same template in AMP as non-AMP. Also, you’ll be able to write theme templates the normal way in WordPress. You can still override templates for AMP responses, however. To do that, you’ll need to specify a template_dir.

For example, if you want to serve a different single.php in AMP than non-AMP, you can create a directory like amp-templates in your theme and then put a single.php inside of it; you then tell the plugin about this directory via adding this to your theme’s functions.php:

add_theme_support( 'amp', array(
	'template_dir' => 'amp-templates',
) );

For more on this, see https://amp-wp.org/documentation/how-the-plugin-works/amp-plugin-serving-strategies/

Nevertheless, it is better to not override the template if you can help it. The AMP version should ideally be the same as the non-AMP version. If you need to have two separate template partials in the template for AMP vs non-AMP, you can use the is_amp_endpoint() function in the theme’s regular template file to check if it is rendering an AMP page or not. For example:

if ( function_exists( 'is_amp_endpoint' ) && is_amp_endpoint() ) {
    // Put AMP code here.
} else {
    // Put non-AMP code here.
}

In this way, you don’t need to create an entirely separate template file.

Thanks Weston!
I just wanted to say how much I appreciate your detailed answers, they are super helpful, So Thanks!

Few small clarifications –
the function – is_amp_endpoint() canot use also in the classic mode right?

and btw – do you have any option within the plugin that helps somehow implement custom-scripts support?

Few small clarifications –
the function – is_amp_endpoint() canot use also in the classic mode right?

This is not relevant in Reader mode (formerly Classic) because in Reader mode dedicated AMP templates are used, distinct from non-AMP templates. It is only relevant in Standard/Transitional modes where templates are shared between AMP and non-AMP.

and btw – do you have any option within the plugin that helps somehow implement custom-scripts support?

I don’t understand. What custom scripts specifically? To do what?

Thanks.
basically I’m trying to add my custom scripts logics and i know it’s a tough task with amp and i was wondering if there is any pre implement CDN through the plugin.

not an important issue, thanks again.

What specific functionality are you wanting custom scripts for?

for now just a basics click events and stuff like that.
import google \ facebook pixels and other services

You should be looking at using AMP components instead of writing custom scripts for such functionality: https://amp.dev/documentation/components/