ART!
Deluxe Unhuman
There's always a way to make it work.
Off the top of my head, as a not-yet-fully-grown person, give her some ability score minuses and/or some roll or rolls that she will have disadvantage on.
Then - and here's the important part - give her some trait or feat or knowledge that makes her indispensable for this mission. I don't know ToA, so I have no suggestions there. How many times have we seen the spunky kid who the adult characters reralize they have to take along with them, despite their misgivings?
Possibly useful:
Playing Younger Characters - D&D 5E
Child class (DM's Guild, free)
Off the top of my head, as a not-yet-fully-grown person, give her some ability score minuses and/or some roll or rolls that she will have disadvantage on.
Then - and here's the important part - give her some trait or feat or knowledge that makes her indispensable for this mission. I don't know ToA, so I have no suggestions there. How many times have we seen the spunky kid who the adult characters reralize they have to take along with them, despite their misgivings?
Possibly useful:
Playing Younger Characters - D&D 5E
Child class (DM's Guild, free)