Clarification, did she actually escape or was she just standing up or chewing at the edges of the pen? Its normal for a rabbit to explore the edges of a new environment, don’t worry too much about it! As long as least 3 ft high, she will probably not be able to jump it.
Puppy pens are great for sectioning off rooms, and giving rabbits more space. we have one blocking off our TV area (Thor is free roam, but there are too many cords to bunny proof in there!). After the pen is in place for a while, she will probably get used to it being there and stop trying to escape.
If you are taking her outside, make sure you keep a CLOSE eye on her at all times. Rabbits can dig under fences pretty quickly and you want to prevent an escape. Unfortunately this is how I lost my childhood rabbit, he got out of his backyard pen. Don’t want to scare you, just a word of warning that they really must be constantly supervised outside to avoid predation and escapes.