What does the cat do to let you know it wants to go outside?

We tried once to take her indoor to see what she would have done. We brought her inside, closed the door and then took some steps away to give her space and don't make her feel pressured, we were there looking but at a safe distance. She initially tried to open the door unsuccessfully and then after roaming in the house found a window I had left open in another room (I wasn't expecting her to go there) and jumped out to go back outside (I live and ground floor). From there I haven't repeated this experiment because I'm afraid she doesn't like staying indoors and she might suffer if I force her