Alkan's '3 Grands Études' Op.76 are virtuosic studies pushing the boundaries of piano technique. They are known for their extreme demands on the performer, requiring immense dexterity and power.
Mastering the immense technical challenges, particularly the octave and arpeggio passages, is crucial.
3 Grandes Études (Op.76) is rated Henle level 9 of 9 — virtuoso repertoire, roughly concert / virtuoso level. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 9 — meaning you can already play level 8–9 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 3 Grandes Études (Op.76) lasts about 25 minutes.
3 Grandes Études (Op.76) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.