For the future of this current timeline, pretty easily. Cryogenic freezing if it ever becomes possible to be thawed out, or by traveling very very fast. Also being by being next to something extremely dense like a blackhole time will move slower for you.

For backwards time travel the first stipulation is to be involved in the deepstate or secret government projects as it would never be allowed for the public most likely. To actually travel backwards into another universe or timeline the bending of spacetime would need to occur, you would basically have to be moving in negative speeds, or at least stiller than still itself. you could possibly use very tightly controlled singularities or blackholes to bend time and space making you arrive sometime in the past. To return to your original time you would need some kind of GPS tracker that can analyze and memorize certain key attributes from the original setting point which would be different from the past. The singularities and the tracking system would also have to work together which almost seems laughably complicated.

Also if wormholes big enough for humans to travel through actually exist thats possible as well.