Does the multi-focal length of a hot shoe flash need to be the same as the lens?

No need. The focal length of the hot shoe flash does not need to be the same as the focal length of the lens. A hot shoe flash is an independent photography device. Its focal length refers to the angle of the flash, which is used to control the beam angle and range of the flash. The focal length of a lens refers to its viewing angle range, which is used to control the field of view and magnification of the photo.