How to make a mesh system - Eero 6

Hi all! I've currently got a single Eero 6 and whilst my house isn't big, its noticeable slow when using wifi in the furthest rooms.

I know there are mesh packs of three, but since I have one already could I simply just purchase one more (total 2) to get better coverage? I can just use the 2nd one on wifi right, so it will only need to be connected to power.

Thanks!