Create inverted masking with Shapes to make cool effects.
First add a shape to the canvas, in this tutorial we're going to use a circle.
Add a custom scale animation and set the scale to 0.
Right-click on the Circle clip and select Duplicate.
Right-click on the duplicated circle and select Mask with > Circle.
Select the mask clip and choose Yes for Inverted.
Offset the mask animation a bit to make the first circle scale before the mask animation start.
Click the Shape Mask clip and add 1 or 2 to the Scale, i.e. if the Scale is 70 make it 71 to hide the circle outline.