A large number of phrasal verbs are formed with the particles up and down. Sometimes, these have meanings that are more or less opposite, for example round up (to increase a number to the nearest whole number) and round down (to reduce a number to the nearest whole number).
In numerous other cases, the meanings are far from being opposite, for example bring up (raise a child or start discussing a subject) and bring down (to cause a government or a politician to lose power).
There are also a number of verbs that are formed with one of these particles but, regrettably, do not exist with the other. You can butter someone up, for example, (be especially nice to them so they will help or support you) but you can't butter someone down. Likewise, mess up (to make a mistake or do something badly, as in ‘She says she completely messed up the interview’) has no equivalent with down, nor do carve up (to divide something valuable and share it between different people, organizations or countries, especially in a way that seems unfair), crop up (appear or happen suddenly or unexpectedly, as in 'I’m going to be late. Something’s cropped up’) and mug up (quickly learn something or check that you know it, for example before an examination).
Conversely, you can knuckle down (start working hard), you can simmer down (become calm after being angry) and you can dampen down someone’s hopes or expectations (make them less strong) but none of these can form phrasal verbs with up to reverse the action or situation.