How do I enable the roughness of the models in the material settings? In Blender, you can enable bumps and valleys, how to achieve the same result in UE4?

With Physically-Based Rendering (PBR), Roughness is how polished something is. 0 roughness is reflective, 1 is matte.

You must be talking about normal maps.

I want my machine gun to look like this in the game, and not differently

You need a normal map, as stated above:

And the intro to materials:

You will need to import a special Map associated with this mesh and plug it in here:

It emulates light hitting irregular / uneven surfaces making the impression that the mesh is more detailed and complex.

That is, in a blender you need to create a normal map of this texture and then import it into ue4? And connect to normal. It is a pity that there is simply no checkbox in an unreal engine like in a blender. Why is texcoord there? I’m thinking of watching a video on how to create a normal map in blender. Thank you.
Will there be outline of the model then?
This greatly improves any model, I think you will agree with me! I am in favor of all models with normal maps. All my models will have normal maps. It’s amazing how these two automata differ, and I have been doing modeling for a long time, but I did not know about such a thing.

Can I just bake this thing into a texture in a blender?

Normal maps have been in use for a long time and they will be in use for some time to come. You will need to study them, especially if you’re a modeller:

The answers to your questions are readily available on YT:

And if this video does not work for you / you do not like it for some reason, there’s always another video, another blog, another tutorial and another forum thread about it.

it takes a very long time for me to bake 4096

And if I bake on the main texture and just overlay it on the model, me won’t need a normal map?

52% Is it normal that it takes so long to bake? CPU 97%. Complete 90%
In general, nothing worked for me

Everynone, I did everything as in your video, but for some reason my Kalashnikov turned half black and there is no normal map after processing. And even when combining objects, for performance in UE4, the parts also become black. I will understand what the problem is.