Best Default Form size Phonegap iOS and Android

I’ve been using 320x460 as the default form size for my app, which uses Phonegap for both Android and iOS stores. It’s worked until recently on different phone screen sizes since it’s responsive and adjusts to the longer length screens of many phones.
But since iPhone X things haven’t been working out as well. The screens are now being spread out and showing fonts too small on long phones, like the iPhone X.

I was wondering what the best practise is now for new mobile apps that will run on both Android and iOS, as to what the default form size should be.

Thanks,
Malcolm

The best practice is to make the controls on your form adjust to the size of the form. It’s a bit different way of thinking.

Here’s an article to get you started:
https://wiki.appstudio.dev/Responsive_Design_Made_Simple

Thanks, I am using some of the techniques, but there are a couple more I can try.

Unfortunately the main problem is around font size both in static labels and input fields. Most of the elements on my form are input and text strings showing calculations.

I’m using Bootstrap 3, and while the screen elements spread out and resize quite well, the text gets smaller and smaller as it scales to larger displays. There doesn’t seem to be a way to have the font size increase responsively from what I can see.

Here’s a discussion on font sizes. One of the ways to do this is to make font sizes a percent, rather than a fixed value: