I had a huge problem with Nokia 6.1 fast battery draining and I had to research and contact many of the professionals to get a quick solution on that. What I did to overcome this problem was,
1. First I went to Nokia Care Center and flashed the firmware officially. They installed Android Oreo into the phone and I had to re-check for system updates and update the phone into Android Pie.
2. Once the Pie was installed, I performed a hard reset on my phone and the battery was considerably good.
3. I got rid of the myths that battery needs to be charged into 100% all the time bla bla stuff. Now what I do is, when I had a chance, I always keep my phone plugged in. And when I use the phone only, I unplug it and take it away.
I bought a Baseus Type C Magnetic Cable
to make it easy to charge the phone by just placing it near the port. Now I am getting approx. 1d 8hrs battery life and