“Old age is like a plane flying through a storm. Once you’re aboard, there’s nothing you can do.” -Golda Meir
It’s been 13.8 billion years since the Big Bang for us, and when we look out at a distant object in the Universe, we’re seeing it as it was in the past. Its age — as it appears — is determined only by how long the light took for it to travel from that object to our eyes, but to someone living there, it will also appear that the Universe is 13.8 billion years old.
But it is actually possible for an observer living on another planet, star or galaxy to perceive that significantly less time has passed since the Big Bang, so long as they were moving close to the speed of light relative to the CMB. Paradoxically, if they slowed their speed, they’d find that they themselves were still very young, but living in a 13.8 billion year-old Universe.