It can, by a jeweller who separates links at the joint. The concealed pin or eye at each point is opened, complete links are lifted out of the sequence, and the chain is re-nested and closed at the point where the clasp attaches. The links removed are kept for a later lengthening.
Because every link is identical and faces the same way, there is no count to preserve; any number of links can be taken out. The clasp is re-attached to the end link so that the last point, or the last notch, meets the clasp ring cleanly.
On a chain built in two runs meeting at a centre link, the jeweller removes an equal number from each run so that the centre stays at the centre. The listing notes which construction a particular chain uses.