IMO @Temeura get a complete 8.5" sounds about right. Spend what you can afford, don\t ride it through puddles and don’t leave it out in the rain.
If you have the option, softer wheels as they’re more fun (78a - 90a).
And as @roncalow says, learn how to fall properly. I found jujitsu brilliant as they teach you how to safely fall forwards and backwards (this is a basic). Looks a bit over the top, but after learning this at 19 when I was skating 2-3 hours a day, I haven’t cracked my head or hurt my wrists since (I’m now 42). Learn it with your daughter, it’s a skill you keep for life, you do it automatically after a while, saved me many broken wrists and concussions (including when out on the piss)
How to fall forwards:
How to fall backwards:
