Open any app that uses the keyboard
Tap and hold the keyboard icon in the bottom-right corner
Select Dock and Merge if the keyboard is split or floating
Pinch out on the floating keyboard with two fingers to enlarge it
Drag the floating keyboard to the bottom of the screen to dock it
Go to Settings
Tap Display & Brightness
Tap Display Zoom
Select Larger Text if available
Tap Set
Restart the iPad if needed
Go to Settings
Tap Accessibility
Tap Display & Text Size
Turn on Larger Text
Turn on Bold Text if desired