Hi Woofer,
In general yes. While it would depend to some degree on their size and at 7 1/2 years old their preferences may play a slightly larger role (although I would be careful here because children often prefer things that aren’t particularly good for them) … I would be very cautious about choosing something that was too soft for a child as long as they are still growing and developing into their more adult proportions.
Because of the supportive nature of latex compared to other types of foam … you would probably be “safe” with something a little bit on the softer side of medium but I wouldn’t go any softer than that.
Just as a clarification as well … you won’t find a latex topper that is anything but “100% latex” because synthetic latex and natural latex are both equally “latex”. I’m guessing that you probably meant 100% “natural” latex rather than 100% latex. All the latex you are likely to encounter (Dunlop or Talalay made with either natural or synthetic rubber or a blend of both) will all have been certified by either Oeko-Tex or Eco-Institut for harmful substances and VOC’s (see post #2 here) and I would consider any type of latex to be a “safe” material as well.
There is also more about the different types and blends of latex in post #6 here and there is more about some of the differences between Talalay and Dunlop in post #7 here.
Phoenix