How can you say we in third person?

You can't say "we" in the third person because "we" is inherently a first-person plural pronoun. It refers to the speaker and at least one other person.

Here's how you could rephrase something that uses "we" in the third person:

Instead of: "We are going to the park."

Use: "They are going to the park."

Instead of: "We decided to eat pizza."

Use: "They decided to eat pizza."

If you need to refer to a specific group of people in the third person, you can use their names or use a pronoun like "they," "them," or "those."