What do you think is better to do Buy another PC and if so what PC is the best for the daz or buy one Pc and upgrade it ?
It totally depend of the money you can put in it. But unless you want to make a regular use of DForce, the CPU is less important than the GPU and its memory.
When rendering, Daz Studio put everything (mesh geometry and textures) in the GPU memory, therefore 12 GB is the minimum it should have. There's way to optimize this, by cutting of what will not be on the render, reducing the texture size and all, and script to do this, but it's always better if you can keep the whole scene ; especially the texture size for everything that will be close to the camera.
But before rendering, everything is in the main memory, plus the OS itself, Daz Studio and everything else you can run at this time. What lead to the 32 GB for the RAM. So far I mess with Daz more than anything else, and the 16 GB I initially happened to be relatively short. Since I past to 32Gb, I rarely use more than 16 GB, but when it happen the OS not having to swap it and all really make a difference.
And obviously, the more powerful the GPU will be, the faster Daz will render the scene. If you don't expect to build big scenes, or have a big amount of renders, or have animations, a GeForce 2070 can do it ; I know that many authors still works with it. But if you think you'll need big scenes, many renders or animations, then a 30xx is what you should have.
As for the CPU, an Intel one, or a AMD Ryzen, it depend. DForce need a lot of computation, but generally an Intel CPU just need two/three minutes at most. It would be more comfortable to have a Ryzen, but it's not too killing to not have one.
What you should seek is the best compromise between the power, the price, and the time you can afford to "lost" because Daz is rendering.
By example, if you plan to have just few renders, it's not really a problem if Daz need 30 minutes to generate each one. You can have batch rendering, therefore launch a batch of renders before you left fr works, and one when you'll go to sleep, and you'll have around twenty renders by day. And this would just need an average computer.
But if you really need many renders, then Daz should be able to render with an average of 5 minutes or less. And for this you would need the best in terms of GPU and CPU.