Had this phone since launch, no experimenting nothing, all stock. It's still fast and has decent battery life. This phone is one of the best purchases I ever made up to this
Replace Battery BLP637 For OnePlus 5 5T Five One Plus 5 5T Authentic 3300mAh | eBay
Replacement for OnePlus 6 Battery
Using an old OnePlus phone? Here's how to improve battery life and performance