iphone 6S plus battery drain fast with recent update (13.5/6)

My iphone battery healthy level is 82%. But with recent os update battery drain fast whether i used or not iphone. perviously it show whatsapp background activity used more than 50% of battery. Then i have turned of all background activity. But problem is still same. before i updated my phone when i fully charged it, i can used nearly one day with average 4h screen time. is there any solution for this ?