There's no way the 2080 can run odyssey at upscaled 8k with every single setting maxed out. You've only got 8gb vram for a start with a 2080. My 1080ti is as powerful as your 2080 and you wouldn't expect a 1080ti to run these games at upscaled 8k. Plus the 1080ti has an extra 3gb vram than the 2080.I can max these games with a 2080. You are probably reading that your system is using more than 8GB. But that doesn’t mean you need it. The system can allocate more resources to RAM that is not being used.
I’m sorry but you think you need more than 8GB to max these games then you are flat out wrong. On AC Valhalla with a 3 year old 2080 I’m maxed out with about 80-90fps. There are dozens of benchmarks showing cards with 8GB less running the game maxed out at good frame rates.
Don’t get me wrong the 3090s 24GB is very useful but there’s very very few games that need more than 8GB today. Ray tracing uses a lot of memory so it’s probably most useful there.
Just be prepared, the 4080 or whatever it will be called will be significantly faster and cheaper.
I'll leave this here as we've hit one of those never the twain moments and life's too short to get bogged down by such drivel