301 redirect : newdomain and adding folder. looked everywhere!

I have been searching the forum all day and I can not figure this out!

I need a 301 redirect script that will redirect from:
https://www.olddomain.com/?=243 —> https://www.newdomain/newfolder/?=243

It seems easy to go the other direction but not this way creating a new folder…

I was hoping to find a script that doesn’t utilize a line for every page, but can carry over all the file names.

This is the closest I can determine, but it has not worked..

#RewriteCond %{HTTP_HOST} ^olddomain.com$ [OR]
#RewriteCond %{HTTP_HOST} ^www.olddomain.com$
#RewriteRule ^(.*)$ https://www.newdomain.com/newfolder/$1 [R=301,L]