If your camera has an HDMI output, it's easy. I have a 7" display intended for Video work, that will plug into the HDMI port on your camera. When pluged in, the display stops working and this 7" monitor then displays larger, what the display on the camera shows, but mine isn't a touch screen, so you need to use the controls on the back of the camera when making menu changes. The monitor also has an HDMI output, and I have used a long HDMI cable that I can plug into a flat screen TV or video recorder, etc. , but most TVs aren't adjusted for color correctness very well, like a true monitor, so some recalibration of the TV is usually required, and I wouldn't want to do any photo editing using it.
I don't usually use a TV as a monitor this way, but do have a 46" VISIO flat screen TV on my studio wall, and I have set it up as a 2nd monitor for my laptop PC.
When doing a photo shoot, the TV displays every shot taken as my computer software records it. Both the TV and the PC screen both show the image, but much larger on the TV. Yes, I have recalibrated the colors on the TV, and they are close, but I don't do any editing using it. The TV faces the subject/model, so they can see each shot seconds after I take it, and it has improved their poses rapidly, something like looking in a mirror.
This TV also gets used to watch videos on the internet, but isn't even connected to watch regular broadcast TV. I haven't watched anything on broadcast TV in about 8 years, except occasionally the major news and weather, that my wife might be watching downstairs when I happen by.
Charley