Is there a simple Outline function?

I’ve been trying to do a simple Outline in Scrivener 3 for Mac. I don’t want to have individual documents/folders set up for each main topic. I guess I want to simply do an outline in one document (basically a numbered list. But with a hierarchy the way it can be done in Microsoft Word.)

I know I can do a simple ordered list, but I can’t find any way, for example, to make one item (say Roman numeral one) and have several items under that (Letters A, B, C, etc.) and with numbered items (1., 2…) under those letters.

Is this function possible in Scrivener?

Thank you in advance.