Video calling is a Carrier Specific Feature. In order to use Video calling from your Natvie Phone app, the carrier must authorize the feature and allow it as a feature on your account with them. If they don't support the feature, a third party app would be required in order to make video calls.
Thank you guys for your responses again, but I believe Samsung Cole got it. My S9+ Was under the Carrier of T-Mobile and my S10 plus is under the Carrier of Sprint. I was able on my S9+ to switch from audio calls to video calls. Video calls isn't even an option on my S10+ under my NEW Sprint Carrier for the this device. Thank you again.