We are getting one more level complex on this one.
In this code applied to Circle Stroke, we are linking a bunch of variables, such as Stroke / Circle Min and Max Size. By using ease() expression, we can re-map those values, and add a bit of smoothing at the same time.
The rest of expression is similar to Circle – Size one. However, instead of main layer animation from 0 to 1, we are using Circle Size X value to drive the whole thing. This way, Circle will grow, and it’s size will affect Stroke.
It is basically chaining multiple values together – master one drives animation, then other ones follow.