Merge Folders?

Years ago I stumbled on an excellent feature in the MacOS whereby if I tried to copy a folder to a location with a folder that already had the same name, I would get an option called "Merge", which would brilliantly only copy the items which were either new (and didn't exist in the target folder) or were the same but had a newer modification date. Wow!

But now I'm using Catalina and I can't figure out how to get this feature back. Every time I copy a folder from one location to another, with a definitely newer version of the folder as the source, I only get the usual "stop" or "replace", and never "merge".

"Replace" obviously still does the trick in replacing an older version of the folder with the newer one, but it takes way way way longer.

How do I get the "merge" feature back?