Impossible. Even with the expansion of the universe, planets within a galaxy do not move further apart due to the expansion of the universe. While the universe is indeed expanding, this expansion primarily affects the distance between galaxy clusters, not the distances between objects bound by gravity within a galaxy.
We will not be going to Mars (as in colonizing), in our lifetimes or any time soon. We can send robotic crap with AI maybe.
Most likely scenarios of any advanced civilization visiting other galaxies will involve things that replicate and can move on. Maybe some day in our future we will be able to put human consciousness or whatever into things. Maybe even nano sized things.
Musk's Mars delusions are fired by ego. HE will die and be buried on Earth -- or cremated and sent to Mars as ashes. Good riddance