If you aren't satisfied with the typefaces that come with iOS and iPadOS, you can install and use others. There are several ways to do this. The easiest may be to use the Adobe Creative Cloud app. The app is free. All it ”costs” is a membership in Adobe's world, an Adobe ID. They are free.
Download and open the Creative Cloud app. Then choose the Fonts tab at the bottom. Now you can browse all of Adobe's thousands of fonts. Most cost money, but nearly 2000 of them are free. Tap the blue Install Fonts text when you see a font you like. This will install them on your device.
The fonts you install will be available in apps that support custom installed fonts. This includes Pages, Numbers, and Keynote.