Phrasal verbs are extremely common, and are usually the most natural way to express something. They often sound more informal than their non-phrasal verb counterparts. Idioms are less common. Idioms are more common in formal and poetic language. That's not to say that people don't ever use idioms, but I don't think English speakers use idioms as much as in other languages. Phrasal verbs are among the first words toddlers and and small kids learn when they're learning to speak, probably because it allows them to be far more expressive with a small vocabulary size. They learn more formal, non-phrasal verbs later in life. Conversely, people generally learn idioms at an older age. People learn all the phrasal verbs passively when they're little, but as teenagers or even young adults they might need to look up an idiom's meaning if they haven't heard it before. It's not incommon for adults to encounter new idioms, but it would be very odd for an adult to come across a new phrasal verb.

Phrasal verbs are used a lot in English-written, formal and informally. Idioms are used, but not as frequently. Have a look at this Wikipedia link for phrases verbs: https://en.m.wikipedia.org/wiki/Phrasal_verb