Making a 9 inch Square sponge cake

Hi,
My daughter has been asked to make a square 2 tiered sponge cake.
She is using the Victoria sponge batter as has never baked a Madeira cake before and has never made a cake this big.
She is using a 9” square cake tin. Would 6 eggs, 12oz
batter be ok and should she use one tin or two. I’ve told her it’s best to use two tins as otherwise it will be in the oven too long and may be dry.
Can you give some advice please on the best option or even a recipe.
Regards. Carol