I have to admit that having a battery fail after one year's usage is disappointing but it's certainly not unheard of. Lithium batteries can wear differently depending on all kinds of factors such as the temperature they're used in, how often they're charged and discharged, the age of the battery itself (not necessarily the same as the age of the phone), etc. And of course you could just have a bad battery; one that's worn out prematurely.
I'd suggest starting out by checking your apps' battery usage to see if there's one that's responsible for most of the drain. If you find something, try updating or deleting the app to check if that solves the problem.
If you don't find a software solution, the the next step would be to replace the battery. It's not especially difficult on your phone, but does require some patience and care. Sorry to say that iFixit doesn't have a guide for you but there's a Spanish site called Nadie Me Llama Gallina that has just what you need.
Manuals / OnePlus 10 Pro / Battery
The batteries themselves are a little more expensive than I'm used to dealing with, but nevertheless are readily available on many sites such as Amazon, eBay and AliExpress.