It's a little complicated.
About 6-8 years ago, the NCAA changed its rule book so that schools could begin to offer multi-year scholarships. All the way up to 4 years (5 with redshirt).
So it's an option everywhere.
But most schools don't use that option. Instead, there's usually an unwritten commitment between the players and their programs: you stay in good standing, keep your grades up, no big disciplinary issues, represent the university well, keep dedicated to the team, and we'll keep renewing your scholarship all the way through school.
And they do. You never hear about schools dumping players without cause, just because they didn't (for instance) ever make the two-deep.
In fact, just the opposite--most schools usually find ways to continue to pay for a young man's education even if he gets a career-ending injury and can't play any more. They may shift away from one of the 85 allowed football scholarships, but find another way to keep paying him to finish up.
So no, there aren't many formal 4-year scholarships these days. But there are a lot of year-by-year deals that feel almost just as if they were for the full ride.