Yes, I have had to wrangle young children in the crowd. If they were still in the toddler stage, I would put them in a stroller. Depending on the location, I would sometimes put them in a wagon and pull them.
When they were past the toddler stage and would walk some distances by themselves, they understood that they were not to wonder off without me. I "trained" them to stay close to me.
In areas that were not crowded, I let the toddler walk. It was on those occasions that I let my kids know that they stay close to me. Call it training or conditioning, or whatever you want.
Regardless, I never used a leash and never felt the need to use one. My kids are not my pets.
