Is there any way to use php 8 or hiugher for my laravel 5* project. Please suggest.
I don't want to increase my laravel version but php.
You cannot. Laravel 5.x is compatible with PHP 7.x. If you want to use PHP 8.x you must upgrade your Laravel project.
Here you have the link to check Laravel 5.x requirements:
https://laravel.com/docs/5.7#server-requirements
And here is the Laravel 8 and Laravel 9 server requirements:
https://laravel.com/docs/9.x/releases#php-8
https://laravel.com/docs/8.x/upgrade#php-7.3.0-required
Also here is a package for a fast Laravel upgrade process. :)
https://laravelshift.com/