Hello,
Thank you for contacting Rank Math Support.
Yes, changing your permalink structure will affect all your existing posts automatically. WordPress will also automatically redirect the URL of your old posts to the new one. But this is only applicable to posts. You cannot create redirects for pages, taxonomies, or Custom Post Types.
However, note that changing the permalink structure on a live, indexed site can impact your SEO effort. So it is important to ensure that your old URL gets redirected to the modified one whenever you change it.
If WordPress wasn’t able to create a redirection after you changed it in the settings, then you would need to create the redirection manually. You can check this knowledgebase article on how to Redirect Posts After Changing URLs https://rankmath.com/kb/how-to-redirect-posts-after-changing-urls/
Aside from creating redirections, it is also advisable to resubmit your website to Google sitemap so that Google re-index your site and update your website sitemap.
We hope this helps.
Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.