Hey. Piano teacher here.
When someone starts to learn piano it can take several months/years of practice to get to the point where one can play the music labeled "easy" by publishing companies. I highly recommend finding a book or two made especially for piano by pianists. They know how to make the piano sound awesome even when keeping it simple.
Movie scores are usually very complex and have multiple instruments to make a fuller sound; this can make it sound empty on a piano when you play a beginner arrangement.
Here are some I'd suggest for someone very new to piano (you can even listen to all the music on the website): https://pianopronto.com/composers-community/chrissy-ricker/chrissy-ricker-lets-quest-songbook
Or you could get him a "fake book" and he can learn about adding his own chords to the melody: The Easy Movie Fake Book: 100 Songs in the Key of C https://www.amazon.com/dp/1423425200/ref=cm_sw_r_cp_apa_i_vBN5Db9XE7R80 However, you will need to check that this book has scores/songs from movies he actually likes.