During a rain storm two years ago, my ex-wife drove directly into a flooded underpass in her small crossover. Water up over the bottom of the windows. I mean, there were MANY chances to assess the situation and stop or back up, but I guess those were lost on her. Anyway, obviously the motor went kaput from sucking in water, not to mention the electronics were all fired, and the car was stranded there. My son calls me and asks if I can pick him up and go to the car because he left his phone and other stuff in there when they were evacuated by fire personnel (why wouldn't you jump out of the car and swim/walk to safety of your own accord, I'll never know).
We drive down there and the water had receded from about 5' down to about 3-3.5'. My 60 (without snorkel) had no problem driving right down next to the little crossover. My son actually crawled out my window and directly into the window of the car to get his stuff, didn't even get wet. The nice thing was that when I rolled up to the underpass, the fire department guys blocking the road told me to go on through haha.
So yes, big lifted vehicle = helpful in an emergency. Snorkel is probably a bonus too.