Increase text size only for Messages?

I've followed lots of online guidance,- none of which worked.

If I increase text size so that I can read Messages without my glasses, email and browsing become unusable.

Is there no means of customizing each app?

Lots of times I can't devote two hands to put glasses on and off.

And we call these things smart phones?

Seems like we're doing more and more scrolling, swiping, and hunting than ever before.

If the phone rings, we should be able to pick it up and talk.