@tonezandi Thanks for reaching out!
There are a lot of factors that go into getting a bike fit correctly, but a great starting point is the standover height of the bike and your inseam with shoes on. The size large on the Co-op Cycles ARD 2.1 has a standover height of 31" and the extra large is 32". On a road bike you want to start at about an inch of clearance between your inseam and the standover height. You can read a bit more about how to measure this in the Expert Advice article, Bike Fitting Basics.
The difference between a bike that is too big and a bike that is too small is the difference between being stretched out (putting too much stress on your neck and hands) and being scrunched up (putting too much stress on your arched back and shoulders). You can make some minor adjustments to the location of your saddle (forward or backward) to help dial in the fit. If you need to change out your stem or riser, you can work with your local bike shop to get that taken care of as well.
It is good to consider what level you are now as a rider, and what level you aspire to get to. If you're just starting out as a road rider or getting in to longer distances we would recommend going with the size large frame. It will give you a little bit more upright of a riding position and you can make some adjustments if you need a longer reach. With a 32" inseam your torso shouldn't be too long for a size large frame.
Hopefully this helps!