rewrite URL due to old permalinks

I am helping a customer who has some old links from old posts, search engines, etc. and I thought I would just do something in an .htaccess but its not working.

Permalinks are setup as post name, so I need to have things like the following;

https://domain.com/folder1/folder2/ which used to work and now is a 404. I want that go goto; https://domain.com/folder1/newfolder/

So as you see that example is buried under folder1.

I have a few more that folder1 will change such as;
domain.com/folder5/folder6 will become
domain.com/folder9/folder6

Is there any way to do this at the wordpress level and if not, what would be the correct syntax in an htaccess. I thought it would be something like;

Redirect 301 /folder1/folder2 /folder1/newfolder

Thanks to all read/replies.