Iphone 8 Plus Battery Draining Too Fast

My Iphone 8 Plus battery is draining entirely too fast though I have been using much less the last several days. This seems to have occurred since the previous software update. Prior to that, the battery only needed to be charged once a day. Now I am having to recharge 2 to 3 times a day with very little use of the phone. I have researched and changed several setting that could have contributed to the issue, but the drain is continuing.