If you have ever downloaded YouTube on any Apple device using your current Apple ID, you can download an older version directly. Open the on your iOS 12.5.7 device. Tap your Profile Icon in the top-right corner. Go to Purchased > My Purchases . Search for YouTube . Tap the Cloud icon (download arrow) next to it.
A pop-up will appear saying: "Do you want to download the last compatible version?" Tap . download youtube ios 1257 link