New race skis do come better prepared than recreational skis, but even so, if you want a proper race ski, the first thing to do after receiving the package is to take it to a shop, to have it tuned. Normally a 0.5 base and a 3-degree side is good enough for racing technical skis. Maybe go 0.75 / 3 if you don't actually ski hardpack (i.e. blue ice). Other criteria include how well you ski and what shape you're in...
No real need to pullback the sidewall a lot, if you don't ski ice, as long as you can polish the edge without filling the stones with plastic...
The FIS designation simply means they conform to FIS norms. The 21m doesn't sound like one, I think even FIS masters race 25m now (I think) and everyone else 30m GS skis. They used to race 23m/27m a long time ago, then 30/35m and now 30m. If you want to know the current regulations, look up "FIS ICR 2019 equipment" or something like that - you're looking for the equipment spec in the ICR. For SL the radius is not regulated, just the length and some elements of the sidecut I think - but they tend to be around 13m. If they're less than 12, it's not a real race ski, likely a detuned master's ski.
Race skis are built beefier, that's what we like about them, the "race" feel. However, they are meant for racing on ice and many rec skis are pretty close when not on ice, especially master's mini GS skis (Fischer RC comes to mind). Also, many rec skis are pretty beefy, say the Head i.Speed line, the Head Monsters etc. They're also more friendly and give you this "race" feel in many conditions, especially out west... if I were to take one pair with me, it would be the Head Monster 88s. 83s are not bad either, for the nice groomers y'all ski there... you can bend those into almost a slalom turn shape, and they'll hold on groomers, not on ice...
I would not necessarily buy
new race skis if you're not racing. Used FIS skis are the best deal around, not only because they're cheaper, but they're also broken in and more predictable and nicer feel, especially if they have some edge left
.