Help looking for story in ENM

[gobbwgo]

Help. Looking for story in ENM where there is story of huge size and age comparison between teenage boy and young girl. Teenage boy is much older say around the 15 to 17 years old vs a young bigger junior girl of around under 10 years old. The young girl is taller and bigger than the older teenage boy…like a “taller younger sister” etc. If you point to some stories of that theme I will appreciate it thanks.