This WILL erase ALL data from your device. Then, if you run into a situation like I did, where Google Device Manager and/or Samsung Find My Device functions for resetting the password fail, REMOVE your micro-SD card & do a FACTORY RESET. BEFORE YOU SET ANY LOCK PIN/PASSWORD/PATTERN-REGISTER YOUR PHONE ON A SAMSUNG ACCOUNT! Enable auto-backups of apps/themes/SMS/texts/contacts, etc, in the Samsung Account, save all media that you can to the micro-SD card (back this up too on PC), then proceed with your lock settings. After you get a new device, install a micro-SD card & load all your desired apps.
Prevent a seemingly unsolvable phone lock-out=here is some straightforward & common-sense advice.