Her smile could rival the Mona Lisa's. - Allusion. - An allusion is when another thing from something well-know is referenced in a sentence or poem.
Who knew you two were due to ... aachoo! - imagery. The word "aachoo!" creates an image of someone sneezing.
Ollie owns orange owls. - Alliteration. An alliteration is a sentence/poem where the words start with the same letter or sound.
I hope this helpsss xx