Homeowners and sitters who haven't met

Just left a sit in Ft Worth that I didn’t meet the HO on either end. She has had multiple sitters and I am the first that she didn’t meet before the sit.
3 big dogs (200 lbs across 3 dogs) - 2 x 2 yo bernedoodles and 1 x 8 yo flat coat and 2 outdoor cats.
Went just fine. I’m concerned about going off-lead with dogs who I’ve not been ‘introduced’ to. Took these guys to the dog park and although they all had great fun splashing in the pond and playing with other dogs, as soon as I walked in another direction, they followed me.