Configuring WordPress Auth Cookie Expiration

Note that you’re not adding any filter callback with:

apply_filters( 'auth_cookie_expiration', $expiration );

Instead use:

add_filter( 'auth_cookie_expiration', $callback, 10, 3 );

where $callback is the appropriate filter callback that modifies the expiration.

Here’s an example

add_filter( 'auth_cookie_expiration', function( $length, $user_id, $remember ) {
    return $length; // adjust this to your needs.
}, 10, 3 );

or to fit with your current class setup:

add_filter( 'auth_cookie_expiration', [ $this, 'set_auth_cookie_expiration' ], 10, 3 );

where set_auth_cookie_expiration() is the appropriate method, e.g.:

public function set_auth_cookie_expiration ( $length, $user_id, $remember ) 
{
    return $length; // adjust this to your needs.
}