Can you put me a pc together worth up to 1200 euro?

So first that would be very nice

The pc should be well suited to streaming and whoever I play privately should play fortnite 120fps to over 200fps and others like gta5 and do well and water cooling (if you suggest one) which is easy to build and if anyone else does Just want to ask please.

Währe the first pc I build because of this no selfmade water cooling

If you have the parts, who will build it then? Without knowledge I see only disadvantages with a selbstgezimmerten PC. I can't recommend it under these conditions, but if you want to assemble it yourself and risk breaking individual parts, take a look at these recommendations: https://www.computerbase.de/forum/threads/der-ideale-gaming-pc-spiele-pc-selbst-zusammenstellen.215394/#text-build750

Have a look at Hardwaredealz
There's always something there!