My Battery is draining so fast!!!

so i bought my iphone 11 on 1st of November 2019 , everything was normal with the phone till the battery health started dropping 1% after like a month and a half or two (which i think is pretty normal) after that every months or two it dropped by 1% , but lately it dropped by 6 % in just one month! which to me is frustrating because i really take care of my phone , my old iphone is 87% after using it for 3 and a half years so when a new phone drops by 9% in one year is bizarre and new to me .

what should i do ?