Hi and welcome aboard.
One of the BIG problems with just scaling is getting the engineering right.
The footprint of the machine and its work envelope all determine the size of; the linear ways (so they don't flex and give you crappy resolution), the size and style of the linear drive (screws/belts/chain/racks), and naturally the size of the power supply, motors and drivers.
You - probably knew all that. Quite a few of the folks here build a first machine - to spec -- than learn from it and then build a larger machine using it to get the parts built. How big are you looking? 8x4 (feet) or? There are some other plans out there that can get you to a larger machine on first go if your want to jump right in at a bigger size.
Pretty sure other guys will chime in here too.