Why would you want large fish - they will usually grow on their own. I am planning on having lionfish in the tank and want as little possibility to create a meal for the lions as I can
Especially clarkii and the like will grow to a good size in as little as a year in the right sized tank. The only ones I found to grow extremely inconsistently are percula.
As for the second part - pairing a small one with a large is usually possible if you do it right. A large one will usually be a female already and therefore be less aggressive to a small male than when both still have to fight out their place in the hierarchy. Only the introduction has to be done right, ideally in a neutral tank where both are added at the same time.