the idea that you can only fuck up and express and be beautiful and destructive and explorative and constructive in your youth is simply a myth. you are going to continue to fuck up and you are going to continue to blossom. there's no linear path and structure on that. even people in their 50's completely change their entire lives. nothing is fixed and there is no path to follow.
your life isn't over until it's over.
this narrative that once you start to age you can no longer explore and express is an oppressive, capitalist, and intentional one. also, it's just not true.
your responsibility doesn't have to be boring or restrictive. the reason why you become more responsible is because you actually care about yourself. irresponsibility isn't the same as freedom. irresponsibility can be "fun" but also destroys you. having more responsibilities to keep yourself safe and cared for isn't the antithesis to fun and life and expression.
your feelings make sense though. in college it's easier to meet people and try new things. but ease doesn't translate to quality or longevity or intrigue. but funny enough, there are 30 year olds now that probably feel the exact same way about you as you feel about the people slightly younger than you.
there is no such thing as free years in terms of spirit.
expression and exploration is available in all forms at all ages. there are always places to go, hikes to walk, friends to laugh with, mistakes to make, good food to eat, art to create, fights to have, things to fail at, lessons to be learned, and love to be felt.
you're only 23. you're about to enter a new chapter of your life where you will fuck up and you will have stories to tell, adventure to explore, feelings to express, and people to love. and that is something that will always be true.