Basically, after a certain amount of character size, default animations completely stop working, is there any fix or some sort of workaround for this?
Hey!
If you want to enlarge the character without affecting the animation, I recommend you to change within the parameters of “Humanoid > HumanoidDescription > Size, etc…” you will have several parameters to enlarge/shrink the character or modify to your liking without affecting it. In case it doesn’t work, I don’t know how else to help you 
Right now, i’m changing the size with Humanoid.HeadScale.Value and the other ones, but that messes up the animations after a certain value, is this what you meant?