End of Course Challenge

Link to Video: https://we.tl/t-Ssaw8kc9a2
Theme/Inspiration: Mariokart powerups
Great tutorial video! I have little previous experience in Blender from other tutorials but this course helped me understand keyframe animation, as I had only experimented with rigid body animations before this.
Question: is it possible to change the color of a HDRI? I would have liked the color of the grass to match with the grass I created. Also UV mapping is tough. Is there a way to copy-paste an image texture onto each face of my cube so I don't have to individually edit each face to look the same?
Thanks,
Kabir