agam

John, I would love to understand more about how the Redirection plugin can be used to do this job without problems?
I emphasize,

1. This domain: https://www.example.com/ currently has an active website with excellent results and it does not work on an old system, otherwise there is currently no WordPress system installed on this domain.
2. This subdomain https://www.new.example.com/ is built on the WordPress system and we built the new website on it, I installed the Redirection plugin.

The final result should be like this: all the pages on the subdomain https://www.new.example.com/ are directed to the correct pages (the subdomain will no longer be active).
Domain https://www.example.com/ will work on the WordPress system and will become the new website.