Yep - as above, something around a 12700K (or 5900X?) should be the target CPU.
That said, even from your 6 core Xeon, just about any Alderlake (12th Gen Intel) or Ryzen 5000 series is going to be a significant step up for you... even a 5600X would be about 50% quicker (clock speed + IPC improvements).... and that's a great little CPU, but it would be a shame to bottleneck that 3080Ti and hamstringing it with any 11th gen Intel / or 3xxx Ryzen.
To do the gfx card any justice aim for a minimum of a 12600KF or 5800X... 5600X at an absolute push, but you'd be holding the graphics back for some games.... so if you scrimp there, make sure you build the rest of the rig with plans to expand that to a 12700KF/5900X at a later date.
MickyFlinn's suggestion is solid, a few observations:
1) you'll need to go win11 with a 12th gen Intel.
2) Not a problem, but he has scrimped a little on the storage, SN750 would be better-matched, but that SN550 is a solid drive and TBH - that will get a genuine 2500-3000Mb/sec.... so will still be nearly 10x faster than anything that would fit on a Westmere Xeon like yours (300Mb/s SATA2 max, normally - most likely closer to 250Mb/sec even with a top spec SSD!)... stick with it.
3) I'm nowhere near as confident on the PSU's - especially your older one.... 850W might sound a lot, but even at stock speeds, that graphics card (350W+), a 12700K (250W+) will be drawing 600W already under extreme conditions.... add on peaks of 250W for the Z690.... you will already be at the limits for that PSU - and that's assuming that the PSU can deliver the full 850W to those three devices with the correct split. Granted, those would be pretty extreme loads, especially for the chipset, but that is what they are rated to be able to draw and the GPU + CPU will definitely see brief peaks at those levels during peak load, especially if you want ot run a few benchmarks. If I was building that, I'd aim for 850W on the equivalent X570+5900X build, but probably ~950W on the PSU for that build to give yourself a little wriggle room.
edit: I had a spec for my next upgrade plans (5900X + 3080Ti) in a forecast tool (name is forum blocked as it links to other retailers). The tool was showing just under 700W for my build, so I swapped out the X570 motherboard and CPU for a Z690 and i7-12700K.... and the wattage jumped up to 800W. Note this includes a few drives (2 NVME, 2 SATA, 2 optical), 4 sticks of RAM, etc, but it means the 850W PSU would be running at around 90%-95%, which feels a little high. With the E-cores on the Intel, this does NOT mean your power bills will be higher while the system is left idle, etc... but it does mean you might want a little more power headroom (hence the 950W recommendation) with the Intel options.
My personal preference would be a Ryzen 5900X and Asus X570-PRO as I'm still wary of Win11, but the 12th gen Intel chips are very valid choices and it really is in the balance right now (Dec2021): as the win11 task schedulers learn to cope with the new Intel architecture, I can see the Intel building out a bit more of a lead with them purely with software updates. That split-architecture (efficiency + performance) is likely to be the future and given how power hungry and hot Intel's performance cores have been for the last few generations, they really needed another gear... which they now have with the efficiency cores for idle / web browsing, etc.
