How to convert a date to the month-end date using the LAST_DAY() function?

LAST_DAY(date) is a MySQL built-in function that returns the month-end date from a given date. For example:

SELECT LAST_DAY('2020-02-14'), LAST_DAY(NOW()), NOW();
  -- +------------------------+-----------------+---------------------+
  -- | LAST_DAY('2020-02-14') | LAST_DAY(NOW()) | NOW()               |
  -- +------------------------+-----------------+---------------------+
  -- | 2020-02-29             | 2023-11-30      | 2023-11-15 08:33:35 |
  -- +------------------------+-----------------+---------------------+

Reference information of the LAST_DAY() function:

LAST_DAY(date): dt
  Takes a date or datetime value and returns the corresponding value for
  the last day of the month. Returns NULL if the argument is invalid.

Arguments, return value and availability:
  date: Required. The date to be converted from.
  dt: Return value. The month-end date.
  Available since MySQL 4.

⇒ LOCALTIME() - Synonym for NOW()

⇐ HOUR() - Hours of Time

⇑ MySQL Functions on Date and Time

⇑⇑ MySQL Function References