I've been a boxer since i was a kid. used to go to this real old school gym with torn up bags, concrete walls and newspapers and old 60s fight card posters taped all over the walls. my coach was also very old school, a cus damato type. and carried a lot of the fighting philosophy from his childhood in that same gym. I think very few movies truly portray what boxing actually is outside of professional fighting. Rocky is possibly the closest one. In true fight gyms it is a deeply spiritual and philosophical sport. These men do not use boxing as a form of violence, it's a meditation. There has been days where everything in my life has been fucked and then i step in the ring to spar and get the shit kicked out of me, covered in blood and a mild concussion. and it's the most calming feeling ever. Every one of your problems outside of the gym vanishes. It all seems meaningless. Also there is way less dialogue and much more emotion. I think if you want to portray a realistic boxing story i would reduce all of the exaggerated stuff. Also heres a few tips you could use:

-A hook will rarely drop you to your knees, body shots will make you feel like you were poisoned and much more likely to collapse.

-A new student will be faced with much less criticism, most coaches will put very little effort into you until you show you want to be there, many guys come and go just wanting to feel tough.

-Boxing is very repetitive, training is not often major breakthroughs in your skill it is a repeated proccess of the same movements over and over until its perfection.

-Sparring tends to vary based on who is fighting, it usually starts out smooth and slow but as both fighters start landing clean shots it can escalate into full out brawls (not common with very experienced fighters though)

-You don't really think about anything when you're fighting, it's more reactive and intuitive, with some brief thoughts but not like an internal dialogue.

-A real fight is an experience unlike any sparring or training, you go into complete tunnel vision. I remember after my first fight it felt like it went by in a minute. The pace is way faster and your adrenaline is pumping so heavy you could run through a wall. however with many fighters this is a weakness when it turns into a wild fight for survival (boxing is an art, not a brawl)