If you would rather keep the current sized balance, this could be a bit of an undesirable change as it makes it easier for other people to see your balance if you are using the app around them (and most people probably want to keep it private).
I think a potentially better option would be to improve the app’s dynamic text support to allow the balance to “grow” in size if you increase your system text size.
This is definitely possible on iOS, but I don’t know enough about Android to know how feasible it would be.
The “standard” mode would then keep the text the same size as now.