Yes, because the Mi 5v2a charging head is in line with the USB charging standard, and the Apple 11 also supports USB charging, and you only need to use the original Apple Lightning to USB-C data cable. Although the output voltage of the charging head is slightly lower than the fast charge protocol supported by the Apple 11, it can meet basic charging needs. It should be noted that the use of non-original charging head and data cable may affect the charging speed and safety, it is recommended to choose a formal channel to buy original accessories.
It can be used, and it will not cause any damage to the phone, but it is best to use the Apple original cable to charge, in the Apple original data cable, there is an mfi certification, and it is safer to charge with this data cable.