One handy expression to know in After Effects is the valueAtTime expression. This tells AE to grab a value from a property at a specific time. You can pull values from properties such as position, scale, and more! You can also use math to delay or alter the value at a specified time.
In this example, I show how to use the valueAtTime expression to have one layer follow the scale property of another. You will also learn how to target another layer’s properties while writing expressions, including learning about the index expression.
Please enjoy this short video tutorial: