I made these for a friend’s kids, one 6-year old and twin 3-year olds. The fitted ones are from a pattern I found on the internet, don’t have the site right now. I modified the pleated ones using the sizes below to cut the fabric rectangles.
Child 4-7 Cut 5 x 7 inches
Child 2-4 Cut 4 x 6 inches
Edited to add website
Www.craftpassion.com/face-mask-sewing-pattern
It has adult and children’s sizes. It also has options for ties.