Lanamoden Authentic Austrian Girls 3 4 Trachten Dress Dirndl 2pc Set 100% Wool
There are no sizes on the garments so I measured and used an online size chart, please check the measurements below to confirm they will fit your child:
Cardigan measures 12" from pit topit and 13" long.
Dress has adjustable buttons on the straps so the length can be adjusted. Waist measures approx 10" when flat.

Authentic Trachten dress from Austria in very nice condition, there are some faint stains as shown in the last 2 photos, since this is wool it will need to be dry cleaned so I did not try to remove them.