You can find a number of collections of illustrations for the Palm Sunday story at FreeBibleImages.org.
It is a great source for Bible story images, no matter what art style or format you are looking for.
Here is a peek at the Palm Sunday illustrations from Lambsongs: (they are also available in black and white - great for coloring sheets)
You will also find illustrations there that may work better for older students, such as these from Sweet Publishing:
And there are great photos stills from the Lumo Project film, too! (https://www.lumoproject.com/)
Free online Palm Fronds with suggestions for use - from Illustrated Ministry. Great for church members at home during a virtual worship service to have something to wave.
Also something the kids can take home to display on their front door or window.
Illustrated Ministry has a FREE Alleluia Poster that you can color and share -- on your door, window, mailbox, wherever it will be seen. Link to the zip file for downloading and instructions are here: https://www.illustratedministr...eluia-poster-easter/