Asking on behalf since the family doesn’t know what to do !

A child was born in Thailand but parents are both Foreigners. The child lived in Thailand untill 15 without visa. But right before Covid,the child’s father went back to his country to seek for medical assistance. The child and mom are left in Thailand. When covid happened, the child and mom left Thailand from Myanmar boarder since the mom is Burmese. So the exist stamp was never there in the passport. Now the child is almost 18.

Let’s say the child go back into Thailand from the boarder and wants exist the country (Thailand)on her foreign passport by plane. What will happen to her?

Since she is passed 15 years of age where her visa free period is done.

Will she get banned from Thailand for overstaying 2 years without visa?

Or is there anything the family can do ?

P.S the father is dead while he went back to his country.