Hi, stable water parameters within target values goes a long way, and alot of light and flow. Supplemental feeding with sertain types of coral foods geared toward small polyped corals can help but I am not sure about the science there.
I agree that the best thing is stable, adequate water conditions with high light and high flow. That's ideal for most SPS (though not all!), especially acros. You could also try dosing amino acids like acropower, though I've never personally tried that.
Use AcroPower from Two Little Fishies to provide amino acids to your corals to help build their skeletal structure. Amino acids can easily deplete in reef aquarium systems through protein skimmers and ultra low nutrient systems. Replenish amino acids for colorful and healthy corals. Specifically...
I had several acros and sps in my 90 gallon .With viper spectra lighting several years back when I get had a heavily packed acro / sps mixed tank . I dosed acropower
(17ml) a day and had a ton of growth and color out of all my sps.
Basically the same as what has been said, stability, with alot of light and flow (but do remember to acclimate your corals to the lighting intensity gradually increasing and toning it down or moving your corals lower if you see signs of bleaching).
Also, what I have learned so far is that for SPS and also to some extend all corals, Flow>Lighting. Lighting is important no doubt but in my experience flow can make or break your tank. I generally notice that my SPS love turbulent flow (flow that goes in all directions, clashing with one another). I used to have laminar flow (single direction flow) in my tank and notice that they dont grow as well. I guess turbulent flow makes sure flow hits the coral from all sides. Basically you have to play around with your powerheads to get that nice random polyp movement (seeing them sway in all directions). If you have SPS with alot of polyps like montis, porites and corals from the pocilloporidae family, I’d suggest using frags of them as like “measurements” of your flow patterns. Like for me, I use my pocillopora to adjust the best flow rate and pattern for my tank. If the poci is happy, everyone else is happy.
This is anecdotal but maybe occasionally feeding fine particle food (rotifers, zooplankton) may help. But ultimately I believe getting the right flow will do the trick.
Do also check out youtube videos by Tidal Gardens, Bulk Reef Supply and MileHighReefer to just name a few. They do share really valuable insights when it comes to coral care.