This is actually a little complicated compared to what taxpayers usually have to deal with, but according to the proposed regulations (which will be the on-point authority for 2018), you don't need an entity, you need to have your real estate activities rise to the level of a Section 162 trade or business.
Probably, you would benefit from this post:
Section 199A Rental Property Trade or Business DefinitionBut note the basic rule is, your real estate investing needs to regular, continuous and conducted with a profit motive. (Again, though, if you're really interested in this, read the blog post. That'll give you deep background.)
P.S. If you really want to dig into the weeds on this, you probably ought to also look at this blog post's discussion of the draft instructions, in particular the points about the rental business requirement:
https://evergreensmallbusiness.com/irs-pub-535-section-199a/