Here`s a suggestion for a option in TPT.
If you open options and press bigger screen the simulation would be bigger.
It will act the same as the gravity and air simulation option; saving would keep the option on/off
Flame/comment here below for further questions, comments and suggestions.
Xetalim
https://powdertoy.co.uk/Wiki/W/Full-screen_how-to.html
A quick search on the Wiki should turn up helpful info.