Both suggestions are great.

I would love a plant! Or flowers, something consumable like chocolates, etc.

Don’t bring a plant. Don’t bring anything that is essentially a chore. Bring baked goods, chocolates or a bottle of wine.

What is the relationship if you've never met them but will spend the night? A baked good is a kind gesture.

Either is fine. I think bringing two things would be overkill.

I am going to visit a family I have never met. I will have dinner and spend the night.

Is it enough to bring a homemade baked good (for breakfast the next morning), or should I also bring a plant? (They do not drink wine.) Thanks.