iPhone SE screen too small for some apps

PREAMBLE FOR CONTEXT (skippable): I rarely install apps as I find it just too burdensome to research the security implications. I store some pretty private information on my phone, so I stay away from apps (for the most part) and have always kept off the cloud. I'm from the Casio Personal Digital Assistant days, when you had small black and grey LCD screens whose pixels were very much visible. Address book information was hand typed using real keys, and porting data off electronically was a novel concept.

On the rare occassion when I do install an app, I have found that it was designed for larger screen phones. Essential parts of the display reside below the bottom edge of the iPhone SE screen. Some pages of some apps allow scrolling/panning, but not always. Sometimes, it seems that they assumed that no one would have a phone so small as to be unable to access the bottom portions of the content, so the content doesn't scroll, and I can't access the bottom parts.

For example, some parts of the Tim Hortons app for reward points allows you to redeem points for food/beverages, but some parts of the menu becomes inaccessible. Another example is an app to access a certain vendor's security camera; it requires that you create an account with the company, but I can only access the login fields -- not the links to create an account. I don't know if I can use a friend's bigger phone to create an account, but even if I could, the controls for access the video are also way down, and would be accessible using my iPhone SE.

I tried using a pinch gesture to shrink the size of the content so that the content lower down on the page would fit on the screen. Resizing of the content doesn't seem to be possible.

The iPhone SE is not a rare phone. I can't be the only one butting against this problem. How do people deal with this?