Ok lots of good stuff been said above. As a tall woman with tall children now very lean teenagers, I would be very happy for you to message me to talk it through if you'd like to.
Looking at the charts, your daughter is probably around 15 cm taller than average for her age, the reality in her immediate peer group will then vary by chance and who is old/young in the class. So yes I can well imagine she is 20 cm taller than her friends. As a child I was generally "a head" taller than my younger sister; and in turn she was usually about the size of my own classmates. As a young child I was literally "off the charts" and apparently they would just look at whether height and weight were in proportion to check I was ok.
Now, as to your daughter - she is definitely a healthy weight and one of the best things you can do is provide her with a good range of healthy food and allow her to eat to her appetite. That way she can remain in touch with her appetite.
I do understand what you mean about dance and gymnastics. Children who are tall tend to be growing faster much of the time and are often less flexible than their shorter peers. That lack of flexibility can have an impact on what they can achieve. BUT, at the age of 7 these are great activities and she should be encouraged to keep enjoying them and aim for personal improvement.
The other thing that may well be noticeable size wise, is that if she is more or less in proportion, she will be wider than many of her peers. Children don't change width all that much from perhaps 4 or 5, until early puberty. So you may perceive your daughter as "heavy build" from that when she is not, and without anything else changing will probably look lovely and lean by the age of 12 or (much) earlier.