[[pdoField? &id=`15` &field=`publishedon`
[[*publishedon:strtotime:date=`%Y-%m-%d`]]
This question has been answered by Bruno17. See the first response.
[[pdoField:strtotime:date=`%Y-%m-%d`? &id=`15` &field=`publishedon` ]]
[[pdoField:date=`%Y-%m-%d`? &id=`15` &field=`publishedon` ]]