When you give someone ‘free rein’ you give them the freedom to behave the way that they want or to make decisions independently. This expression is especially used to talk about children having ‘free rein’ or in creative careers having ‘free rein’ over a project without restrictions. This is a phrase you will hear used in both social and professional contexts.

1. The pianist gave free rein to his emotions as he played the classical piece to a sold out concert hall.
2. I don't believe in giving children too many rules. I like to give them free rein to learn things for themselves.

1. When the owner of the restaurant appointed me as manger, she said that I would be given free rein to run things as I see fit.
2. Due to my track record of success when it comes to creating designs, I get free rein to produce whatever I like without any outside restrictions.