500 Internal Server Error can be tricky to troubleshoot but is mainly caused due to your hosting service.
Below are some of the possible causes that might trigger a 500 error on your site:
You can directly contact your hosting service provider for fixing the 500 error or can refer to the article guide here to try a fix for the above-listed issues: https://www.wpbeginner.com/wp-tutorials/how-to-fix-the-internal-server-error-in-wordpress/
Please ensure that your hosting service provides the features recommended by WordPress.
If you are looking for better WordPress hosting, check out this review of the best WordPress hosting providers.