How to make 3d Decals I have created some geometry and want to make a 3d decals like the Decal Machine Addon. Is there anyway to make without addon a 3D decal.

I have created 1 decal but its flat not a 3d.

I want to create this type of 3d decal from the decal machine addon how to achieve without addon.
3d Decal
Not sure if this is the result you're looking for, but if it is you can unwrap your object, projecting the UV-map from view (hotkey U). And then move and scale the UV-map over the normal texture (decal image.png).

Then when you apply the material to your object, it will look like this:

Edit:
(because comments do not allow for enough characters)
I thought you made a nice decal, and if you wanted it to be more 3D you could add it to your 3D model. I thought that was clear. Maybe a bit silly of me because i understand that often the point of using decals is to minimize the use of actual 3D geometry, So i did some digging.
It seems the Decal Machine Addon does not simply use normal maps. It adds to the illusion of geometry using parralax mapping or parralax occlusion. I don't know enough about it, but i believe that is currently not easy to do with Blender alone (hence, i suppose, the existence of the Decal Machine Addon)
Here are some resources on the subject (that also have .blend files implementing the technique):
https://devtalk.blender.org/t/parralax-occlusion-for-blender-2-8/3641 ,
https://blenderartists.org/t/parallax-shader-with-silhouette-clipping-for-blender-2-8-eevee-and-cycles/1162334
and
https://blenderartists.org/t/parallax-mapping-with-silhouette-clipping-shader-node/561285
They might be of more use to you than my answer