It has no concept of certainty, unless it was embedded in the original data. What you are describing is an more general AI. This is a language model. I like to think of it of a cognitive intelligence: the ability to process input and compare it to a stunning array of trained data that will have many parallels to reality but has no concept of it.

It can be trained some form of trustfulness, and a measure of certainty is intrinsically part of the model (compare with image to text models etc "70% cheetah 10% dog")

In any case it can be trained to assert confidence via a side channel