Tiny bit of oil on palm of your hands (can be almond or jojoba or whatever) and run it through the ringlets and they’ll stay/find themself curly again a lot quicker - always used to work on me when my hair was shorter and a lot more curly
I use my curly hair products for my boys. Curly creme usually.
I’ve found Asda baby detangle spray and that’s good! X
Regular brushing will help train the hair, and maybe see if any kids brands do one of them anti frizz sprays to use after the bath?