How to move one point from many points?

Question

css

Good day. I'm writing SVG + animation but would like to know. How can you move only one point from multiple points?
For example:

d="M 10,10
   L 20,10
   L 20,20
   z"

And I want to animate so that only one point changes its coordinate

d="M 10,10
   L 100,10
   L 20,20
   z"

How to make it be an animation and be written in code?