We (family business) own a few multi-properties. A Quadplex and some duplexes in Michigan.
Have you checked out Wholesale Real Estate (multi-family wholesaling) to look for options?
Go on wholesale real estate websites and real estate websites and set alerts.
Another option: My daddy (RIP) did that for a few of our properties -meaning they were single-family - and he made them into a two-family home/duplex. I would look into fixer-uppers and based on square footage - gut and renovate to a multi-unit.
I really like BiggerPockets.com -- sign up and join the forum. They have lots of resources and people who can offer you info -- or steer you in the right direction.
I read this a few years ago, when I started helping more on our properties. It may be a good read for you.
Another to check out: