In a word no. No scaling. It sucks and many of us have asked for it repeatedly. I'm not sure any progress has been made on this:
https://github.com/kduske/TrenchBroom/issues/871
I used TB2 daily and I am acclimated to not having this feature. For someone coming in fresh I can absolutely understand how frustrating this can be. However, for me the benefits of TB2 far outway its limitations.
I've only had this happen once where I really needed to scale something up. Save your shape as a map file. Bring into Radiant and scale it up. Save as a map and re-open in Tb2. Yes it's a pain, yes it's dumb not to be able to scale brushes or groups. And yes Tb2 is still great.