Hello and welcome to MobileRead!
It's probably best to ask your question in our Android subforum:
https://www.mobileread.com/forums/fo...play.php?f=225
What you want can be easily done with Calibre, but Calibre doesn't run on Android. So perhaps someone else has a suggestion for you. You can ask the moderators to move your post to the Android forum by clicking the report button under your username, on the right side of the karma button.