A simple sparkle or star graphic you can download and drag right onto your art for a lovely glitter effect.
This cute sparkle is an image material you can download and place right on your images if you want to make them sparkle. The graphic is 1200px by 1200px.
I made a tutorial showing how to make a graphic like this in Clip Studio Paint, available over on my YouTube: https://youtu.be/yz1oD-uRXwU
I also have this same image available as a Sparkle Brush, which you can find here: https://assets.clip-studio.com/en-us/detail?id=1991333
Example artwork: "Tiny Thief", by me - Sarrah Wilkinson, AKA MsRedNebula
This graphic is also featured in my tutorial on Clip Studio Tips, 3 Magical Animated Effects: https://tips.clip-studio.com/en-us/articles/7688