When it comes to graphics GDevelop does not have a lot to offer at the moment.
You can change opacity and global color of sprites and that’s about it.
Most visually advanced games are using shaders, normal maps, specular maps, lights and advanced rendering Technics like blending sprites and subtracting one sprite from an other…etc GDevelop do not offer anything like that.
The rendering engine GDevelop is using (Pixi.js) do support all this features but it have been not exposed to us, we can not utilise these advanced graphics features of Pixi.js.
If you know how to code, it is possible to tap in to the rendering engine and play around with it but you need to know JavaScript and need to be very familiar with Pixi.js.
So, if you need any advanced graphics features, GDevelop got not much to offer. Of course you can make nice, detailed and polished graphics but that’s got nothing to do with the engine, it is just art.