MySQL:

TIMESTAMP FUNCTION

Syntax:
TIMESTAMP(expr), TIMESTAMP(expr1,expr2)

With a single argument, this function returns the date or datetime
expression expr as a datetime value. With two arguments, it adds the
time expression expr2 to the date or datetime expression expr1 and
returns the result as a datetime value.

URL: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html

Example

mysql> SELECT TIMESTAMP('2003-12-31');
-> '2003-12-31 00:00:00'
mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00');
-> '2004-01-01 00:00:00'