Restoring MacBook Pro to earlier OS

Apologies for my ignorance here...

I have a macbook pro 15” mid 2010 Which I brought 2nd hand pre loaded with loads of software / programmes. I’ve updated the OS a couple of times from the original Yosemite to El Capitan, currently macOS High Sierra 10.13.6. When I upgraded to High Sierra several pieces of software became incompatible. I’ve done a full time machine backup. If I can downgrade to an earlier OS can I then reinstate just the software programmes from the TM backup?