I just wanted to clarify: His Majesty King Charles III is the oldest person (to the best of my knowledge) to succeed as sovereign in either England or Scotland -- correct?

However, I believe the distinction of the oldest HEIR belongs to the Electress Sophia of Hanover -- correct? Indeed, had she lived to succeed Queen Anne on the British throne, then she (and not the present king) would undoubtedly hold the record for being the oldest person to become the reigning monarch of either England or Scotland ...