64GB internal storage isn't the largest on the market but should do fine for most people. A phone well suited for your kids, or yourself if you need an extra phone.
From Back Market
Xiaomi Redmi 9C NFC 64GB - Blue - Unlocked
OnBuy
Xiaomi Redmi 9C Global Version 6.53 inch 2GB 32GB 13MP Triple Camera 5000mAh MTK Helio G35 Octa core 4G Smartphone