Different Font sizes in same list

Sometimes I get the option on screen (iPhone) to change font size of individual items in a list. At other times this has disappeared and I cannot get the option back.
How do I get this option back?

With the keyboard open, swipe up above the keyboard. Swipe down to make it go away.

It doesn’ matter if you swipe over existing list items. Nothing will happen other than the desired outcome.

Got it thank you!! I’ve been trying for months, and wondering why it sometimes appeared, and sometimes disappeared!!!:rofl::rofl::rofl:
It is SO easy now that I know!!!