Redirect all WordPress users to a very specific page on login.

my_login_redirect.php

<?php
/**
 * Redirect all users to a very specific page on login.
 * This should work no matter what login form/etc you are using.
 * If it doesn't work, maybe the 999 priority needs to be higher.
 * If you want to respect the redirect_to param or earlier callbacks
 * that overwrite it, uncomment the section at the top of the function.
 *
 * You can add this code to your site using the Code Snippets plugin or by
 * placing the code into a custom plugin or your theme's functions.php.
 */
function my_login_redirect( $redirect_to ) {
	// If you'd like to honor previously set redirects, uncomment this section.
	/*
	if ( ! empty( $redirect_to ) ) {
		return $redirect_to;
	}
	*/
	
	// Set your redirect.
	$redirect_to = home_url(); // Use home_url( '/my-page-slug/' ); to use a specific slug/URL on the site.
	
	return $redirect_to;
}
add_filter( 'login_redirect', 'my_login_redirect', 999 );