I just used the Custom Error Page Code Generator available at
HTML Basix which lets you create a custom error page for:
301 Moved Permanently
302 Moved Temporarily
400 Bad Request *
401 Authorization Required *
403 Forbidden *
404 Not Found *
405 Method Not Allowed
408 Request Timed Out
415 Unsupported Media Type
500 Internal Server Error *
501 Not Implemented
502 Bad Gateway
503 Service Unavailable *
504 Gateway Timeout
505 HTTP Version Not Supported
Not many of them are used as much say as 404/401 etc, but I guess it's best to have them in place.