You can buy any type of property as an investment and you can get an investment loan on any type of property.
No matter what, if you do not move into it / part of it, mortgage insurance is not available, so the minimum down payment is going to be 20%.
Some lenders will not lend to you if you’re a first-time home buyer… Though, if you think about it, what’s not smart about living with your parents when you’re young and buying a property as an investment (assuming you get along with your parents, of course)?
If you move into one of the units and the loan amount is not above established loan limits, you can get a conventional conforming loan or one backed by a governmental agency (FHA, VA, USDA). And you can rent the other unit(s). Which means you’ve acquired an investment property, right?
From the point of view of a borrower’s finances, yes. From the point of view of lenders, no. Which is a great thing as that allows that borrower to put down little to no down payment. Yes, people can become real estate investor without having to wait till they have 20%, if they’re willing to live in the property they’re buying.
For true investments, properties the owner does not live in, the options for purchasing a loan with the help of a loan are: