How to adjust Resprite's font size?

Open system's control center(drag down from top-right screen corner), tap "Aa" button, drag up or down to change the font size. Tap "Resprite only" to set font size only for Resprite.

Adjust font size in control center

(If you don't see the Text Size button, add it to Control Center—go to Settings > Control Center, then choose Text Size).

For more info, check out apple's doc.