Yes invite them too

If you ever find yourself wondering, as you are planning an outing with a friend: “Should I invite that other friend too?” If you do, then invite them too.

Not always. Sometimes it’s nice to be just with 1 other person.

But, often it’s nice to share an outing (lunch, walk, coffee) with more than just 1 - adding to the overall experience by adding another perspective.

More is often merrier. It is certainly merrier for the person you just invited.