My rendering looks bad

Every single shader looks like crap.
The Bread kills me the most. How to make realistic donuts?

Learn some tutorials, tips and tricks about Lighting

that’s what your scene is missing right now.

I don’t want photo studio look, that is Three Point Lighting. I want a consumer camera look. As you can see, the plate sits on a wooden table, and the table is near a wall. This is a kitchen.
The light in this image comes from the room, where the donuts are in. There is no additional light in that room. The environment gives all relevant light to everything here. Why would I need artificial light?

check your UVs, check your textures, check your closures mixing.

Without knowing what you have done so far, we cannot help very much.

edit: note that food materials are difficult to accomplish even for a seasoned artist.

You could show me how to make realistic donut/biscuits/gebäck
I have done what you can see on the image.

What I can see is some bad texturing. And an answer for that is: Do good texturing.

Now, if you want some better and more constructive advice or help, we must know a lot more from your scene. Material settings, UV maps, Textures used… well basically a copy of your scene with at least the object (and everything related to it) that is causing a problem, in this case the donuts.

Please read this:

It looks like the uv unwrapping is causing the textures to be distorted. You might try spending more time unwrapping and using the uv editor to adjust until the textures look natural. Here is a kind of quick example. It’s not perfect, but the donut texture looks closer to natural.