It fits trim on my body (broad shoulder/chest narrow waist), this isn't designed for you to put a bunch of layers over.
It's stylish over a henley and jeans around town.
In the woods/mountains this is meant as an active mid layer, with an oversized puffy in your pack to throw over when you're not moving.
I bought my first Testa in late 2019/early 2020 and it's still going strong, this recent purchase was for backups, I have six now, grey/black/green and a backup for each. Sad that this style seems to be discontinued. I hope whatever replaces it keeps the fit.
It's hard to find clothes that fit my body this well without buying oversized then paying extra to get them tailored. To put it in perspective to anyone still on the fence, I own a couple different versions of arcteryx lvl5's and the Testa is better in fit and construction.