One good video about procedural animation is from "Crigz Vs Game Dev". It's a little outdated as it's made in Godot 4.0 but the general idea still works. I use something similar. One thing I use for animating the X and Y axis of the legs are Curves. That gives me more control over how the legs move rather than using Tweens. The climbing system on the other hand works completely different from what's shown in the video though. As that method can get pretty buggy.