Scriabin’s fourth sonata is a bridge between his earlier Chopin-esque romanticism and his later mystical style. It is uniquely structured, consisting of an atmospheric first part and a frenetic, ecstatic finale.
The primary challenge is managing the shifting, lush harmonic palette while maintaining a clear sense of melodic line.
Comparable difficulty and character — good candidates for what to learn next.
Piano Sonata No. 4 in F-sharp major (Op. 30) is rated Henle level 8 of 9 — concert repertoire, roughly diploma level. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 8 — meaning you can already play level 7–8 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Piano Sonata No. 4 in F-sharp major (Op. 30) lasts about 8 minutes.
Piano Sonata No. 4 in F-sharp major (Op. 30) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Étude in D-sharp minor, No. 12 by Aleksandr Scriabin, Vers la flamme by Aleksandr Scriabin, Allegro de concert by Aleksandr Scriabin — see the full similar-pieces list on this page.