Most standard two panel bi-folds use flush bolts to secure them with most standard three panel bi-folds having the same plus a standard lever handle lock setup to secure the third panel or a lever handle which operates a twin bolt locking system.

The three types of flush bolts – flush mounted, surface mounted narrow (older joinery) and surface mounted.

There are also instead of flush bolts twin bolt options with locking and nonlocking options that have a central flat handle that when turned operate the top and bottom bolts via rods running inside the extrusion.

And there is a mortice lock twin bolt type setup which works similar to the twin bolt but is mounted thought the edge of the door like a conventional lock body but it is more robust and takes a 1/2 euro cylinder for the inside locking version. They still have a flat handle but this is fixed into the aluminium joinery not into the lock body like on the twin bolt

Patio Bolts are normally an aftermarket addition to the door.