1 - where did you get that cube? there are no glb files in your filesystem. the godot’s default cube is for prototyping, it has flat faces which is not ideal for most projects. you should use whatever mesh kenneys intended to be used with the texture.
2 - the default is the default. you tweak it for your project.
worldenvironment will have many options, one is ToneMap. unreal color space is ACES or AGx, while unity’s realistic space is Linear. godot offers all these and also two stylistic ones, Reinhart and Filmic. Chose whatever you like.
another thing that is enabled by default is glow. this is not needed for most projects.
3 - you can change the default values in project settings.
At first I changed these parameters and they helped.
I lowered the Tonemap Exposure from 1.0 to 0.3 until I finally start to see the top texture correctly. Then I considered that the blocks looked not bright enough. So I applied Tonemap White from 1.0 to 0.6.
The next problem to solve was the shadows of the block, they look way too dark for this kind of style of textured blocks.
I came up with a solution of employing Environment Ambient Light.
So what I did now is I changed Environment Ambient LightBackground to white and lowered Environment Ambient LightSky Contribution from 1.0 to 0.8. This made blocks increase in exposure. So now I considered lowering tonemap exposure, but later realized that re-setting Tonemap White back to 1.0 fixed the issue.
Not sure if this is a correct way, but at least some progress have been made.
So to summarize overall:
WorldEnvironment
Environment Ambient Light Sky Contribution from 1.0 to 0.8.
Environment Ambient Light Background to white color (#ffffff).
Environment Tonemap White is the default 1.0 .
Environment Tonemap Exposure from 1.0 to 0.3
well, if you want that to be the default for your project, you can save the environment to a file, then go to project settings (advanced enabled)->environment and select your file.