GNU/Linux Mint 20 Installing GeForce Driver Guide
The linked tutorial shows you step-by-step How to Install NVIDIA GeForce Graphics Driver in GNU/Linux Mint 20.x Ulyana/Ulyssa/Uma/Una desktop.
The GeForce Driver Mint 20 Setup is a breeze, requiring just a few straightforward Shell Commands to complete.
Most noteworthy: first try with the Recommended NVIDIA Driver Setup from Apt Mint Repo, and then possibly the Generic for Linux.

GNU/Linux Mint 20 NVIDIA GeForce Driver Installation Guide