Buy one size bigger so they fit over clothes or if she has a taller friend on a play date and they want to dress up together.
My nieces at that age really liked princess inspired dresses that they could wear to school too. So not itchy rustly too long for the monkey bars dresses which they loved for dress up at home or Halloween.
Something like this:
https://www.etsy.com/listing/1213064323/midnight-princess-twirly-soft-dress?click_key=017a3a8fca02f13fc8cae26119242e06d26b24b7%3A1213064323&click_sum=a6e56ef5&ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=cinderella+dress+girls&ref=sr_gallery-1-31&organic_search_click=1
Not suggesting that actual dress since
I only know their mom got them on Etsy, but that’s the idea.