MySQLのDATETIME型のフォーマット

Y-m-d H:i:s

The DATETIME type is used for values that contain both date and time parts. MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'.

MySQL :: MySQL 8.0 Reference Manual :: 11.3.1 The DATE, DATETIME, and TIMESTAMP Types

CarbonだとtoDateTimeString()でこれに変換できる

ISO 8601形式など、上記以外の形式を与えるとどうなる？