This is a cadenza written by John Field for Mozart's Concerto No. 25, reflecting 19th-century stylistic sensibilities. It is distinct for incorporating virtuosic flourish patterns common in the early Romantic era.
Technical control of rapid scale passages and arpeggiated figures is essential for maintaining momentum.
Comparable difficulty and character — good candidates for what to learn next.
Cadenza of 1st Movement - Piano Concerto Kv 503 Mozart is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 Cadenza of 1st Movement - Piano Concerto Kv 503 Mozart lasts about 2 minutes.
Cadenza of 1st Movement - Piano Concerto Kv 503 Mozart 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 Belfagor by Ottorino Respighi, Au galop by Vincent d' Indy, Allegro di bravura by Carl Maria von Weber — see the full similar-pieces list on this page.