Is the confi very good / good?

I will soon assemble my new budget PC without graphics card and wanted to know if the configuration is good for under 350 euro!

- Aerocool Cylon mini

- Ryzen 3 2200g

- 16gb g.skill aegis

- 240gb patriot burst

- ASRock AB350M pro4

- be quiet! Power system 9

In the future I would upgrade then only with a 1tb HDD and then with a RX 570 needed. Should I change anything else? Play only minecraft at the beginning!

I think it's ok but rather a B450 motherboard

All right, except the memory is much too little.

So:

At Ram you should definitely! Take 2x8gb ram modules as the dual channel in the system will give you a lot of performance. In addition, you should make sure to take a fast Ram as possible (for example, 3200mhz). One more point of criticism is the mainboard, here you should rather take a B450 board like the B450 m per vdh of Msi. Cheap but very well equipped, but above all you can overclock. The rest is really good.

Overclocking is a bad idea. Feels almost nothing, device becomes unstable, life is shortened.

Of course it brings something especially with an Apu.
Device does not become unstable such a nonsense. If you do it completely wrong it may be so but today there are tools that do it automatically.
If proper cooling is provided then not much will happen during the lifetime.

Is Dual Channel but a total of 16gb! And a B450 Pro4 from ASRock should be enough

That's why I put it after 1tb HDD

What do you think, why the manufacturers do not set a higher frequency as standard?

Because the CPU just becomes unreliable above the set frequency.