What effect does the coronation have after accession had already taken place upon the predecessor’s passing?

Question

Does it have any actual consequence on the state of affairs for the monarch?

Answer 1

Other than the oath (see the Coronation Oath Act), nothing at the ceremony has any legal significance. The coronation is a "symbolic formality." The reign begins at the moment of the preceding monarch's death.

The Coronation Oath, in which the monarch swears to govern the peoples of the United Kingdom and the Commonwealth Realms “according to their respective laws and customs” is the only aspect of the ceremony which is required by law.

https://commonslibrary.parliament.uk/research-briefings/cbp-9412/