This is possible with the Types style. You can group and merge values together. Check out this blog:
I don't have the most recent version of Online so do not see this option. And I'm in New Map Viewer.
I'd like to group all "Other" together - there are even more than are shown in this screen shot.
At the bottom of the list do you see a line for other values. You can drag those others into that section by clicking on the 6 dot button and dragging it into the other section.
Thanks, that works part way. The only problem is that now when I click that feature in the map the popup box shows it as "Other" rather than what it actually is. Maybe there's no way around that.