I had my battery replaced by Apple on my XS. I was down to about 80% life, maybe less. I have seen a very noticeable improvement in battery life. It seems to charge faster when I’m using it on a charger. And before I was losing like 40% of my battery overnight while my phone sat here. Now it’s maybe 2 or 3%.
If you go with Apple they also replace your speaker since it’s integrated or something? They also accidentally cracked my screen when replacing battery, so I got a new battery, new speaker, and brand new screen for like $80 or $90. Definitely breathed new life into my phone.