iPad Pro 12.9 (6th gen) battery draining quickly

Hi everyone, I bought my iPad about 20 days ago and I’ve noticed that the battery is draining too fast. Today I’ve used it for 3 hours (2 hours on Notability (with Apple Pencil) taking notes, and another hour playing Homescapes) and the battery dropped from 100% up to 10%. What shall I do?! Any help would be greatly appreciated, xx