Legend resizing - maximum font size?

[KeithAddison1]

There seems to be a maximum font size baked somewhere in the labyrinth of legend size controls.  I can make it resize upon dragging it out to be larger, but past some point the legend items and text doesn't get larger.  Clearly there is a maximum font size somewhere, where is that setting?

[DuncanHornby]

I can set excessively large font sizes through this route:

Click on video to enlarge.

[AubriKinghorn]

The Maximum font size is the text size set for that text group (description/title/label/group name/etc). Just like @DuncanHornby shows, you can select the text symbol to change the maximum font size.