How do you structure deals with investors?

[Isaac J Mork]

I recently saw a youtube video with Cody Davis talking about how he used investors to buy multi unit building

The math was like if he could raise the rents $83/mo per unit on a 6 unit building at a 6% cap rate it would add about $100,000 of equity.

He mentioned something like he needed 90k and the investor could double their money. That's kind of how he set it up.  I may be wrong but I am assuming if he missed a payment the investor would be entitled to that $100k in new equity.

Now I am wondering how are you structuring the deal with the investors? does that new $100k in equity get a cash out refi and payoff the investors? Are the investors a 30% partner on that property forever?

What resources are out there with how to structure deals like that?