Is dale's smile was as bright as the sun a metaphor oronomatopoeia?

It is neither a metaphor nor onamonapia. That would be a simile.

A metaphor is a comparison.

A simile is a comparison using like or as.

Onomonapia is sound effect Words.

"Dale's smile was as bright asthe sun."

This statement compares his smile to the sun using "as", so it is a simile.