Hi,
if you search the forum for “MPK Mini Plus” you get quite a few results. Just remember to leave blank spaces in between the words. I accidentally posted my answer in a thread that I linked below, so you will find one somehwere on top these days, too.
You can also create your own Remote Script with the Assistant in Cubase, it is actually not very complicated. Here is a tutorial to get you started:
There is also a shortcut to get what you want. Since Cubase does not offer a Remote Script for the MPK Mini Plus you could also download one that was made from another user in this forum, for example here:
I hope this helps. Happy XMas days!