Object boosts use many different things (crates, enemies, friendly NPCs) to get OoB. The general method was discovered by SephJul in 2016, and many different variations have been found since.
All object clips use the same general steps.
Get the puppy trapped between an object and a wall.
Turn around.
Jump OoB.
When the object is something that moves, is becomes much harder. Underground crate clip is a great place to start trying object clips.