I think that is a really cool idea but maybe she got them from the fire spirit or something and didn't tell anyone. But I don't think super strength really suits Anna's character

What if Elsa makes a little mini Olaf as his buddy. Also what if they all split up again and no one knows where Elsa went because she didn't tell anyone but she takes the fire spirit with her and Kristoff and Anna leave to go find Elsa and so do Sven and Olaf and they end up all getting separated and Olaf Sven and "mini Olaf" all get lost and so on