How can I find someone to adopt me as a 20 year old?
Most adult adoptions are among people with an existing relationship. A step parent who has raised a child for years for instance. It is unlikely as an adult that you will find a random stranger to adopt you.
Adult adoption is rare. There is no foster care system that promotes adult adoption as there is for children. You have no right to adult adoption. The closest thing I can think of is joining the military. The military then becomes your 'family,' and you will be entitled to military benefits.
@ 20 it's more of a sugar daddy or sugar momma you are looking for.
pit bulls bite
getting married is more common
You are going to have to find a life long companion to care for you now sweetheart.