Hi, I’m cooking a slow cooker brisket for a party.itll take me an hr to travel will it be ok to plug back in to keep warm when I get there?

I would think so, but I would also place the cooker in a large cooler or cardboard box surrounded on all sides, including top and bottom, with a thick layer of towels or blankets as additional insulation. Plug back in on High when you reach your destination and bring back up to temp as quickly as you can.