direct object or adverb - an infinitive verb

Hi, JasonHouston,

@JasonHouston posted:

A closer look at the numbers behind summer vacation shows the growing importance of holiday weekends, which helps explain how travel has defied predictions of its demise to emerge from the pandemic stronger than ever.

Is the infinitive verb "to emerge from the pandemic stronger than ever" the direct object of verb "defied" or an adverb to define "defied"?

Neither of the two. That is a resultative infinitive clause that shares the same subject ("travel") but is neither the object nor an adverbial adjunct of the verb "defy." Notice that the embedded clause can be paraphrased as follows:

- [...] how travel has defied predictions of its demise and has emerged from the pandemic stronger than ever

A closer look at the numbers behind summer vacation shows the growing importance of holiday weekends, which helps explain [how travel has defied predictions of its demise to emerge from the pandemic stronger than ever].

I'm inclined to say that the underlined infinitival clause is an adjunct in clause structure. It functions as a modifier in the bracketed clause, where it indicates a resultant or subsequent meaning.