www.makemkv.com

I had the impression that MakeMKV had the ability to reduce the file size of the original DVD/Blueray file to users need. Cannot find this function, so I presume I was wrong.
Anyone confirm or deny my impression?

I can confirm that MakeMKV doesn't and has never supported re-encoding.

The only way to reduce the file size with it is removing streams you don't need/want (keeping only English audio tracks and removing the rest, for example).

Thank you. That answers my question. On my first uses of MakeMKV it worked fine and I seem to remember that I did remove the un-necessary audio.

Removing audio streams won't really reduce the files all that much.
(We still do it, though)

Running HandBrake or a similar encoder, though...

With the default settings, HB will reduce the filesize to one fourth or less.
(Working on the Jeeves & Wooster TV series right now, and 2.2 GB files end up between 500 and 600MB. )
There are some exceptions, though, such as the old Charlie Chaplin B/W movies which doesn't really reduce all that much.