@ems101 When my oldest was 4 / 5 I had two go-to options.
The first was Minki nappies -
I'd suggest Xl Standard Mini nappies
You can get them here
My eldest was smaller so in size Large but I used two ptit dessous bamboo inserts with two easy peasy hemp inserts underneath and they were really reliable (and he was a ridiculously heavy wetter). It's about getting enough absorbency into the pocket- Hemp is great at holding a lot of liquid while being relatively slim and not leaking when squished. I also put them towards the front to suit boy wees - you'd need to load the pocket to suit a girl.
I also used wee notions night nappies with additional hemp boosters and well-lanolised wool shorties over the top (though these might be too bulky for a 6 year old.)