Not a tiebreaker, but far more than that. Legacy status more than quadruples the chances of admission of high stats White applicants like the OP.
@“Bill Marsh” based on the Harvard lawsuit documents, the admission rates of legacies and donors in the top academic deciles is above 56%-60%. It may not be that high now, but with his profile, @ethanbmcc’s chance, as a primary legacy, puts him in the match/high match range, not the reach or high reach ranges.
However, it is not a safety, and a match still has even chances of being rejected…