It depends on the place. Wendy's and BK have low carb cesear, but McDonalds cesear is 4g for 2 tbsp. I have no clue on regular resteraunts.

I always order a cesear though, just because it seems the best option besides ranch, and that can vary wildly from place to place too.

When I did LF I took a bottle of dressing with me places. You can always try that