I used to do this, and then I found it’s just too logistically challenging in most cases and wasn’t making me perform any better. YMMV. Certainly a swim, but I’ve found swimming and a small amount of race-pace running is plenty for Sprints. I found that trying to get in all three in some kind of structured warmup in addition to all the other stuff you have to do before the race added to pre-race anxiety and just made it harder to relax, which is already hard enough for most of us before our races.
I like to pay the $10 or whatever for a reserved transition spot in local races, too. There’s something sublime about showing up like 45 minutes prior to the gun, setting everything up, quick run, wetsuit on, quick swim and go. I don’t miss the days of being among the first to show up at the race site just to sit there for two and a half hours or whatever and have to wait in line to pee like six times.
This is certainly true for me, within reason. It doesn’t really scale. I warm up the same way for Olys and Sprints: ~10 min of running with a couple of race-pace surges of 30s or so, wetsuit on, go swim and all that stuff I wrote before. 70.3+, just the swim.