Buttons Too Small in iOS & iPadOS

You could look at using Zoom in Accessibility, might be more hassle than it's worth though?

Zoom in on the iPhone screen - Apple Support

I just tested it quick by turning on the switch in Settings > Accessibility > Zoom, turn on the switch for Zoom.

When you do this a window will overlay on the screen. You can play with it to see how it works..

I double tapped the screen with 3 fingers, the window goes away.

Then I went into Safari and double tapped with fingers to simulate wanting to see a larger 'back' button. The window comes back and you can drag it around your screen by tap and dragging on the oval part of the bottom border.

double tap again with 3 fingers once you've navigated back and the window will go away

tap the 2 overlapping squares to fan out all your open safari tabs, double tap with 3 fingers again.

drag the zoom window over the tabs where the X is..

if it's not zoomed in far enough, triple tap with 3 fingers and a menu will open with a zoom in/out slider. slide it right to zoom in further. Tap outside the menu to make it go away. Tap the X to close the tab. Double tap with 3 fingers to get rid of the zoom window.

So maybe a bit clunky, but if you are having trouble it might help?

Product Feedback - Apple

Increasing text size will not increase button size. You can increase the zoom on the devices, that can make a slight difference. It would depend on what buttons you are referring to.