It can be done, but will get pricey quickly.
Personally, I went with my fully loaded Momentum over an Inscription, as the price difference was about 5K, and that would have only included visual-only exterior items, the leatherette upper dash, and a different interior trim. It's a bit different in the later model years, but my '18 Momentum is more loaded than most Inscription trims were, based on the choices at my dealer lot at the time. Shrug.
I actually don't like the look of the Inscription exterior on the XC60? And especially for my T6 P*, I much prefer the Momentum tail pipes. So if it were me, I wouldn't change the exterior at all...
I've confirmed with the dealer parts department that you can swap most interior trim pieces. Some things like interior lights are trickier (or expensive) to swap, but can theoretically be done. You'll need VIDA, some same-year/same-market VINs to reference, and a lot of time and patience though.
That said, if you really do want the entire Inscription look for whatever reason, it'll be cheaper to sell/swap your car and simply pay the price difference that way.
Don't worry about being a "poser" though. Literally no one cares if you're swapping parts to make your 55K car look like a 60K car. Personally, I wouldn't put an "inscription" badge on the back? Since that's a little shaddy, but if you wanna swap a few interior trim pieces, go for it. Just know it'll get costly, quickly.