There are 353 4-letter words starting with S in the ENABLE dictionary — 9% of all 3,903 words at this length. S is a one-point tile, so the value in this list is positional rather than numerical — which of these you can play depends far more on where it fits the board than on what it scores.
The list divides into 16 groups by second letter, the largest being the 46 words with so. Scanning the right group is faster than reading the whole list, which is why it is broken up below rather than run alphabetically.
If you know more than one letter, this page stops being the fast way to find it. Enter what you have in the unscrambler — the Contains, Starts with and Ends with filters combine, and setting both length fields to 4 narrows this list to the handful your letters actually allow.
All 353 words, by second letter
SA… (42)
sabe sabs sack sacs sade sadi safe saga sage sago sags sagy said sail sain sake saki sale sall salp sals salt same samp sand sane sang sank sans saps sard sari sark sash sass sate sati saul save sawn saws says
seal seam sear seas seat secs sect seed seek seel seem seen seep seer sees sego segs seif seis self sell sels seme semi send sene sent sept sera sere serf sers seta sets sett sewn sews sext sexy
sial sibb sibs sice sick sics side sift sigh sign sike sild silk sill silo silt sima simp sims sine sing sinh sink sins sipe sips sire sirs site sith sits size sizy
soak soap soar sobs sock soda sods sofa soft soil soja soke sola sold sole soli solo sols soma some sone song sons sook soon soot soph sops sora sorb sord sore sori sorn sort soth sots souk soul soup sour sous sown sows soya soys