Making a dataframe from values over certain threshold in another dataframe

world!

Suppose I have a huge dataframe, and make its jointplot, and see 3 outliners. Apperently these should be over the mediane. I want to quick identify these. Thus how can I write such a condition that a dataframe shall consist of certain value (mediane, or a some high quantie). Another way to reach the same aim would be to select a given number of maximal values in a column.

Could Ye please advise codes for these? Thank you.