What can I do to help my 6 month old cockapoo be more comfortable on walks and in the park?

All dogs (and living things) have thresholds for comfort. Some dogs are confident everywhere but many others, especially young dogs, are reluctant to leave their familiar territory. Their confidence usually grows with experience and maturity but in the meantime I would work on a skill we call engagement. It's an interaction with your dog that you first teach at home and it becomes extremely useful in the face of distraction or if the dog is feeling unsure. It's a process that isn't done in a day or a week, but I use it in many different situations and environments for the life of my dogs. With nervous or young dogs, teaching them to engage on a verbal cue can be a big confidence boost for them. They gain comfort for knowing what to expect.

I will link some material for you to consider below.