Not necessarily. You will find such small locker boxes with charging device also in places without a designated bicycle parking area*. Again it is a separate object so I think it should get it’s own amenity tag.

Imo the first question is: Is the primary purpose a locker for bike equipment (or small luggage) and the secondary purpose the charging facility or vice versa? Depending upon that an option would be

amenity=luggage_locker + additional tags for the charging facility
or
amenity=charging_station (+charging details) + additional tag for the storage box

Only in case this locker charger boxes are seen as a completely different device, neither a luggage locker nor a charging station, but something special only for bicycle users like

“bicycle equipment storage box including power connection”

we should go for a completey new amenity tag imo. In this case we should consider that these boxes allow charging of other devices than bike batteries also, like @dieterdreist already pointed out.

*I tagged one recently here.