How to potty train in public?

I just started potty training my two year old boy. He is doing great. We stay home so he is used to just going potty here. We just had our first outing and it did not go so well, mainly because I’m not sure how to make him use a public toilet. At home he has his step stool so he can stand up to go. So when we went in public he refused to sit down, and it was just a giant disaster. Help me guys… Do I just force him to sit down to go?