Having issues with your camera viewport being too small or too large in Blender? To set this up follow the guide below to solve your problem.

1. Select the camera view (top right icon) or press Numpad 0 to look through the camera viewport.A darker grey tint frame appears indicates you are in the camera perspective.

2. Press the Home key on the keyboard. This will enlarge your camera screen size to the viewport.

3. Hold down Ctrl and Middle Mouse Button or Use the Mouse Scroll Wheel to enlarge or reduce camera frame size.

4. Press N to toggle sidebar. Move mouse down to Lock Camera to View. Check this box to lock your view to the camera. [...]