High contrast text separates the text from the background color, making the text more visible. It makes it easier for some users to read the text on the screen.
Setting method:
realme UI 3.0 & above versions: Settings > Search "Accessibility" in the settings > Accessibility > Vision > High contrast text
realme UI 2.0 & 1.0: Settings > Additional Settings > Accessibility > High contrast text
realme UI R & Go & U & T & S Edition: Settings > Accessibility > High contrast text