Equinox Grid is an Adult grid. Every region, every sim, every estate, every parcel is adult. There is no place for real people under the age of 18 on Equinox Grid. There is no place for avatars looking as though they are under the age of 18 on Equinox Grid.
Unfortunately, to allow avatars that look under the age of 18 on the grid infers that Equinox Grid supports child pornography, which it does not.
Unfortunately, this is a judgment call. You may be a 1 foot adult, you may be an 8 foot child. Regardless how tall you are, your appearance must be Adult!