Most cruise operators can arrange small touches for a special occasion — a cake, a decorated cabin, a better table for dinner, or occasionally a complimentary cabin upgrade if availability allows — but this generally needs to be requested in advance rather than assumed as automatic.
How to actually make it happen
Mentioning the occasion clearly when booking, and confirming again a week or so before sailing, is the most reliable way to make sure it happens, since these requests pass through a booking chain rather than being noted automatically by the ship itself.
Beyond any arranged touches, the setting does a lot of the work on its own — a sunset on deck or an evening at a lit-up temple (see What's the Difference Between Karnak and Luxor Temple? for Luxor Temple's later evening hours) tends to make an occasion feel genuinely special without much orchestration.