How would you use the third bedroom?

[Purnug]

Mum with two young kids. Eldest is 2 and youngest is 2 months old.

I'm moving into a 3 bed flat for a year.
Should the third room be a playroom, a nursery (baby sleeps in a crib next to me for now), a guest room, or anything else?

All bedrooms are all similar sizes

Thank you

Playroom, as children have so many toys. You could have their extra clothes in there too. Good place to store their Lego or a mini desk. A bookcase for them.

Thank you!