Should I move to AM4, AM5, or stay with DDR4 for my RX 6800 XT?

The sensible budget choice is probably to keep your DDR4 and upgrade the CPU and motherboard, or wait until you can afford a proper AM5 setup. An AM4 build only makes sense if you find a very cheap used bundle; buying an expensive high-end AM4 processor such as a 5800X3D would not be good value in this situation. An SSD should also noticeably improve loading and streaming compared with the hard drive, although it won’t fix a CPU bottleneck.

If you choose AM5, avoid building around 16GB of single-channel DDR5. One stick reduces memory bandwidth and can hurt minimum frame rates. A 32GB dual-channel kit, typically two 16GB modules, is a much better target. AM5 offers the best upgrade path, but it may not be worth stretching your budget right now just to end up with slow, single-stick memory.

Before spending money, check whether the CPU is actually limiting you in the games you play. At 1080p, Cyberpunk can be CPU-limited in busy areas, especially with an RX 6800 XT, but at higher resolutions and settings the GPU becomes more important. An i5-11600K could be a relatively inexpensive drop-in upgrade if your motherboard supports it, though the performance increase would be fairly modest.

I wouldn’t move from your current platform to AM4. It would be an older dead-end platform, so the upgrade would give you limited future options. If AM5 is too expensive, keeping DDR4 and moving to a stronger CPU and compatible motherboard is probably the better value. A Core i5-13600KF or 14600KF with a DDR4 B760 board could provide a large improvement without forcing you to buy DDR5 immediately.