numerous large birds sitting on trees.

those are African Sacred Ibis

filmed handheld with 800mm lens, stabilized and slow-motion.

camera Canon EOS R6
lens Canon RF800 / 11

filmed in 4K, 60fps,
edited to 1080p 24fps with slowmotion
sound not original, fantasy noise.

seen near Trino, Italy. Between Torino and Milano. About 55km east of Torino. Province of Vercelli.
along SP 455 just to the NE of Trino.

this field-of-view with 800mm lens only shows a small part of the entire group.
There were probably around 200 of them and also dozens or over 100 of other large white birds, possibly cattle egrets ( not shown in this video ).

here is interesting info about these birds which are native to Africa
https://en.wikipedia.org/wiki/African_sacred_ibis#Europe

fascinating bird gathering.