If you want to get an advanced TOEFL speaking score (26+), then you’ve got to have a good command of vocabulary.
You need to be able to reach for exactly the right word to immediately explain exactly what you mean.
This is NOT the same as learning long lists of synonyms so please don’t do this. It won’t help! Instead, increase your vocabulary organically. Concentrate on learning useful phrases and incorporate these into your speaking.
One way you can do this is by using phrasal verbs. They are incredibly useful in English and they are used in all kinds of language situations. They are often used in place of a more formal, one-word verb. Fluent English speakers will generally choose the phrasal verb because it sounds more conversational and natural.
In my experience, learners of English are reluctant to use phrasal verbs because they are ‘harder’ and, as a result, their language sounds formal compared to fluent English speakers.
So, make an effort to learn and use phrasal verbs in your speaking. You’ll sound more natural.