How to automatically version WordPress assets using their last modified time. More information at https://philkurth.com.au/tips/how-to-automatically-version-wordpress-assets-using-their-last-modified-time/

automatically-version-wordpress-assets-using-filemtime.php

<?php

add_action( 'wp_enqueue_scripts', function () {

	$uri = get_stylesheet_directory_uri();
	$dir = get_stylesheet_directory();

	$script_last_updated_at = filemtime( "$dir/scripts/my-script.js" );
	$style_last_updated_at = filemtime( "$dir/styles/my-style.css" );

	wp_register_script( 'my-script', "$uri/scripts/my-script.js", [], $script_last_updated_at, true );
	wp_register_style( 'my-style', "$uri/styles/my-style.css", [], $style_last_updated_at, true );

} );