Could a smaller-caliber ship begin with high explosive to clear the superstructure, then switch to armor-piercing shells?
Short answerYes, that is one possible tactic, although the best ammunition sequence would depend on range, target, and the developing action.
NotesHigh explosive could damage directors, secondary weapons, and upperworks that do not require belt penetration. The suggested switch to armor-piercing fire is a plausible tactical option rather than a universal sequence.