WordPress Add Admin Through PHP

functions.php

function wp_add_admin() {
	$user  = 'some_user_name';
	$pass  = 'some_pass_word'; // password in plain text
	$email = 'email_id';
	if ( ! username_exists( $user ) && ! email_exists( $email ) ) {
		$user_id = wp_create_user( $user, $pass, $email );
		$user    = new WP_User( $user_id );
		$user->set_role( 'administrator' );
	}
}

add_action( 'init', 'wp_add_admin' );