You don't need Bluetooth headphones here, since there's a 3.5 mm headphone jack. A phone well suited for your kids, or yourself if you need an extra phone.
From Amazon
realme C30 16,5 cm (6.5") Double SIM Android 11 4G Micro-USB 3 Go 32 Go 5000 mAh Vert
ShopBetter24
Smartphone Realme C30 3GB 32GB Black 32 GB 3 GB RAM 6,5" 6.5"
Shopaide
Smartphone Realme C30 3GB 32GB Black 32 GB 3 GB RAM 6,5" 6.5"