Also included: much improved color wheels, color curves and HSL curves. Some very advanced tools for subtle grading and secondary CC.
It's just reframing by making a shot larger than the canvas. In Premiere, adjust Scale to > 100%. In FCP X, adjust Scale to > 100%, or Crop (in the Crop or Ken Burns modes, not Trim. The Ken Burns mode will let you introduce a pan or zoom to a shot rather than just reframing.)
Depending on the project, you can get away with a little reframing of 4K footage in a 4K project, or a lot of reframing of 4K footage in a 1080p project. It won't work for every shot, though, and the more you scale, the better your original shot has to be.
Shooting in a larger format than you plan to deliver gives you better detail and more options. I've certainly used it quite a bit (in non-narrative projects) and it's very useful. You can be a little lazier on set (framing wider than you normally would) and punch in when required in interviews, but don't rely on it to work miracles.
Some really good answers here. One key thing though — don't put too much stock in "what people say" or their opinion that a tool is or is not "professional". Far too many decisions are made on hearsay based on more hearsay, and apps evolve faster than old workflows do.
Edit in whatever you like, learn them all if you can. If you are being paid to get the finished edit into the format you need to deliver, it's "professional".
You can absolutely customize FCP X's keyboard shortcuts as much as you like. In the most recent update, they added shortcuts to select clips above/below the currently selected clip (Command-up/down) and to let the Trim Start/Trim End (aka Top/Tail) commands work on multiple clips at once. Much improved. This article should give you a few advanced examples: https://www.macprovideo.com/hub/final-cut/final-cut-pro-x-the-best-advan... and here's the official list of defaults: https://support.apple.com/kb/ph12724?locale=en_AU
Yep LUTx from CoreMelt, in free or paid versions. If you go paid, you can test out lots of LUTs in a gallery browser, and a single effect which applies both a camera LUT (many Log options built in) and a look LUT.
(Disclosure: I made some of the demo videos for LUTx and other CoreMelt products.)
This can be even faster: I to mark the in. Move to the end. O to mark the out. Delete. Done. You can do the selection with the mouse if you switch to the Range Selection tool first.