Automatically set WordPress Administration Color Scheme to previous default (Fresh) colour scheme for a specific user

functions.php

/**
 * Automatically set Administration Color Scheme to previous default (Fresh) colour scheme for a specific user
 * Replace [insert_username_here] with the relevant username
 */
function set_admin_color_scheme( $color_scheme ) {
	$current_user = wp_get_current_user();
	if ( strtolower( '[insert_username_here]' ) === strtolower( $current_user->user_login ) ) {
		return 'fresh';
	}
	return $color_scheme;
}
add_filter( 'get_user_option_admin_color', 'set_admin_color_scheme', 10 );