Although it doesn't always work as well as it should with some software, the system should automatically switch to your discrete GPU when needed (like when running a game or benchmark), so something doesn't sound right with your software or hardware if the benchmark is running with the integrated cpu graphics.
One thing to check is to make sure you see the 6800M display adapter in device manager and there aren't any errors or problems with it.
As far as I know, the software out of the box should be okay with most software if you want to erase everything and factory reset windows or just reinstall /downgrade the cpu and gpu graphics drivers from the ASUS download page.
https://rog.asus.com/us/laptops/rog-strix/2021-rog-strix-g15-advantage-edition-series/helpdesk_downl...
https://rog.asus.com/forum/showthread.php?125161-Asus-rog-strix-g15-advantage-edition-graphics-card-...
Guessing you purchased the unit from Best Buy and if you're seeing problems with the 6800M in device manager after the factory reset that appear to be hardware related, you may want to talk to Best Buy about getting the hardware checked or replaced if it's necessary and you still are within the return period.
Feel free to discuss and let us know how it goes.