Hi,
The 500 error means that there is some Fatal error in PHP script or on the server side. You can turn on debug mode in WordPress – https://wordpress.org/support/article/debugging-in-wordpress/ to find out what error appears on your site, it will point you in the right direction what needs to be fixed.
Also, you can contact the hosting provider and ask to give you a server error log to check what is wrong.
Regards,
Hung PD