Not most of it - at least on Facebook where there is a LOT posted by people from South Asia and racist/extreme nationalist posters - far more than on Twitter the last time I compared my feeds. For one thing most of it on Facebook is dogwhistle racism not direct. A lot more does not meet the legal standards for creating records. Very little gets reported so no on investigates.
You "could" end up with police at your door, but even if reported most of these things do not meet the requirements for being recorded: https://www.gov.uk/government/publications/non-crime-hate-in...