Hi Nayz, welcome and no, certainly not dumb, it's a common challenge people come across when working with bitmap fonts for the first time. When it comes to fonts like this, unfortunately there's no real in-between--there's no scaling (since that produces artifacts and ends up looking pretty different, usually terrible
) and any different sizes that aren't precise multiples must be drawn manually. So it's either regular size or double (or triple, etc.).
There's an alternative hackish option in the config that allows you to unlock unlimited font size, meaning you can use a large font that doesn't normally fit on your screen (there's more on that in the manual), but doing so requires general familiarity with REXPaint to be able to rely on more hotkeys while also swapping back and forth between the larger size and smaller when necessary.
Otherwise REXPaint 2.0 will one day likely allow for a widescreen format by default and more adjustable UI size, which could allow larger fonts and all the tools to fit on more screens. As is the UI layout is static aside from allowing the creation of an even larger canvas area, though that won't help in your case here. Sorry!