Where are my phone's apps stored on my Mac?

A long time ago, when iTunes backed up my iPhone to my Mac, I could then search my Mac and find all the individual app files inside a subfolder of the "iTunes" folder in my "Music" folder.

But that was then and this is 2019 and I can't see anywhere that these individual files are accessible.

Can they still be found, and if so, where?

Apple doesn’t delete the files out of the iTunes library so if you had old apps they are where they were. Going forward, no apps get saved so there is no new place, just the old one waiting for bit rot to set in or for you to delete your no longer used files.