you could do a wall decal, there are tons of tree ones
https://www.etsy.com/search_results.php?search_type=tag_title&search_query=tree+wall+decal
or you could find a picture you like and use a projector if you're going to paint it.
I am almost finished painting a tree in my nursery (will post pictures when done), but here are a few I used for inspiration:
Re: looking for a picture of a tree silhouette
you could do a wall decal, there are tons of tree ones
https://www.etsy.com/search_results.php?search_type=tag_title&search_query=tree+wall+decal
or you could find a picture you like and use a projector if you're going to paint it.
I am almost finished painting a tree in my nursery (will post pictures when done), but here are a few I used for inspiration: