Every model is a different story, but before you start looking into models, there are a few useful things to know, and a few useful tools that you can use
nvidia
Nvidia is a very popular AI hardware provider, the cool things about modern AI models is that they can be split into layers, hence, you can have more than one card doing the work ! So, I have 2 x 4090 cards doing the work, you can combine the ram to see if your model fits on both when split in half, some models even provide an option to offload some of the model’s data onto the system ram, but that is a story for another day,
To inspect the GPU and RAM usage of your GPUs, you can use the following command
watch -n 0.5 nvidia-smi
The command should show you what processes live in your VRAM (VRAM is your cards ram)