What do your by-laws say about front door locks? Some strata schemes have by-laws which make it an owner’s responsibility to maintain and repair, but this is generally uncommon.
Usually the original lock installed on the front door at the date of registration of the strata plan is common property.
It could be argued by an OC that if an owner or occupier decided to replace a fully functional lock because they wanted a safer lock then the new lock would become the owner’s responsibility and the owner’s personal property and form part of their lot. You could make this quite clear when you apply to have the door hardware changed.
I would be careful not to change the lock to something that is too radically different in appearance from the existing hardware or you may breach the Appearance of a Lot by-law if you have one.