I´ve encountered this issue before and I could never find a clear answer to it. Worst part is that some phones handle it by zooming out while others don´t. Also I remember I found some settings to add (back when I was still building with cordova CLI) but this only worked for some phones and not for others because... reasons? Further, if you maintain a regular app and a webapp, you might find that the same phone handles webapp and regular app differently (one does the zoomout, one doesn´t). I also wouldn´t be surprised if there is differences between browsers too.
I find it to be a pretty convoluted problem (and I think it shouldn´t have to be but what can you do...), and the best solution may actually be to implement your own keyboard and suppress the native keyboard if possible, which it may not be in all cases.
EDIT: I just noticed that you use the preview, try building a debug apk and see how it behaves on the phone. It may work different when build as apk (or not... read above)