Restore old app from previous itunes Backup


Hey all - I have my iPhone 8+ that updated an app that is horrible compared to the previous version. I have the previous version on an iTunes backup on my Mac El Capitan 10.11.6 but apparently iTunes cannot restore a single application anymore. I have iTunes 12.7 on Mac and IOS 12.1 on my iPhone.
Any help or hope with retrieving the previous version?
Have you tried deleting the app, then restoring iPhone without backing up first? (Haven't tried it--YMMV)
However, that may be the only way to restore just THAT app.
Another thought, although again, I haven't tried it, is to use an app like 'unpkg' to extract that one app from your iTunes backup. Worth a try.
Aha, hadn't heard of unpkg. I am also going to give Imazing a try. Sounds like it may do the trick.
Thanks, SGilbert!
Beware that web site is a company that pushes tech support through what appears as an 800 number.