How much for a PC to run RDR2 60 FPS ?

Do you already have any parts, e.g. monitor/peripherals, or are you starting completely from scratch?

You probably didn't double post, Vanilla shows your new post twice briefly.

That would usually mean an AMD GPU would work better with it, unless the VRR on it works okay with an nVidia GPU.

RDR2 isn't that demanding for a PC, an Geforce RTX 3060 Ti, or Radeon 6600XT GPU would give you 60FPS at 1440p.

For 4k that means going up to an RTX 3080/6800 level card though.

Pair one of them with a decent enough and recent 6 core CPU, E.g. Eyzen 5600 or Intel 12600/11500 and 16GB of RAM, and you should be good to go.

The other games are all less demanding, so if you can meet the RDR2 requirements they're also sorted.

Are you building it, or aiming to buy a pre-built?

As an estimate:

RTX 3080, ~€800

Intel i5 12600 ~€280

Motherboard ~€150

16GB DDR4 ~€75

Case ~€75

1TB NVME SSD ~€100

700W PSU ~€80

Decent heatsink or AIO for CPU ~€75 to €150.

So that's €1600 to €1700. That doesn't include an OS, but a Win10/11 key can be bought fairly cheap.

You may want to up the RAM to 32GB, and that's also assuming DDR4 not DDR5.

The current Intel 12th gen CPUs support both DDR4 and DDR5, but the motherboard will only support one or the other, so the choice of board and RAM are linked together.

The GPU cost is the biggest item in there, so you could buy the rest for now, using an iGPU or some cheap basic GPU and add a decent GPU later on.

I screwed up the CPU price, a 12600 is much cheaper than that, I must have enter the 12900 price.

Just as an extra thought. You don't mention what kind of software dev work it is, but if it would benefit from lots of cores/threads, the Ryzen route would allow for a 5950x with 16 cores/32 threads for ~€550.