I upgraded my 4930k PC from Sli 970 cards to a single 3070 and although the CPU is definitely a bottleneck, I've gained some performance and fps increases. I expect a 4070 would work as well as confirmed by aardvark.
Played Robocop Rogue City and was getting 40 to 45 fps at 1440p before I realised the new driver has dlss 4.0 (not upgraded drivers for 2 years!) And after clicking some buttons in the Geforce program I was getting 55 to 60fps and the graphics looked the same to me. Not sure if it dialed down some settings or not but it played great.
I keep getting the itch for a big upgrade as well but just don't use my PC enough to justify it.