I tend to use manual columns in the legend settings since the other options don't leave me with enough control. However, I would love for the font size to automatically change to the largest it can be (still in relative sizes to each other).
For some reason, ArcMap seems to already do this with the following settings:
However, in ArcGIS Pro I had to manually increase the minimum font size until I reached the point where the legend got too large (and then go decrease it again by one).
This means if any changes are made to the legend, I need to play the setting again. Thus, I would love a little button where you can click "Automatically adjust font size to maximum possible".