The topic pretty much says it all, is there’s a way to increase the text font size so my viewers won’t have to squint their eyes?
If you set the overlay to a lower resolution, you can stretch it to increase the size.
So if your base canvas for OBS is 1080p (1920×1080), you can set the overlay resolution to 720p (1280x720) and it should be much more viewable for your viewers. And then stretch the overlay to fit the 1080p canvas size.