Use a Camera’s Render Type property to make it a Base Camera or an Overlay Camera.
To change the type of a Camera in the Unity Editor:
Create or select a Camera in your scene.
In the Camera Inspector, use the Render Type drop-down menu to select a different type of Camera. Select either:
Base to change the Camera to a Base Camera
Overlay to change the Camera to an Overlay Camera
You can change a Camera’s type in a script, by setting the renderType property of the Camera’s Universal Additional Camera Data component, like this:
var cameraData = camera.GetUniversalAdditionalCameraData();
cameraData.renderType = CameraRenderType.Base;