I have connected my TV to the Internet a few times just to update the firmware. Then I turned it right back off again. Not sure if this was actually a great call or not, but I couldn’t help myself. Probably should’ve checked to see if I could do it with a USB drive at least lol.
At least on my TV, I've had firmware updates enable things like variable refresh rate, enable 4K/120Hz, improve the dynamic contrast performance, and fix a couple of weird bugs it had shipped with.
last firmware update I performed for my TV removed features, including the ability to see what resolution and framerate the set was currently displaying.