https://en.wikipedia.org/wiki/Kamala_Harris

Senate presidency

When Harris took office the 117th Congress’s Senate was divided 50–50 between Republicans and Democrats;[193] this meant that she was often called upon to exercise her power to cast tie-breaking votes as president of the Senate. Harris cast her first two tie-breaking votes on February 5. In February and March, Harris’s tie-breaking votes were required to pass the American Rescue Plan Act of 2021 stimulus package Biden proposed, since no Senate Republicans voted for it.[194][195] On July 20, Harris broke Mike Pence’s record for tie-breaking votes in the first year of a vice presidency[196] when she cast the seventh tie-breaking vote in her first six months.[197] She cast 13 tie-breaking votes during her first year in office, the most tie-breaking votes in a single year in U.S. history, surpassing John Adams, who cast 12 in 1790.[197][198] On December 5, 2023, Harris broke the record for the most tie-breaking votes cast by a vice president, casting her 32nd vote, exceeding John C. Calhoun, who cast 31 votes during his nearly eight years in office.[199][200] On November 19, 2021, Harris served as acting president from 10:10 to 11:35 am EST while Biden underwent a colonoscopy.[201] She was the first woman, and the third person overall, to assume the powers and duties of the presidency as acting president of the United States.[202][203][204]

As early as December 2021, Harris was identified as playing a pivotal role in the Biden administration owing to her tie-breaking vote in the evenly divided Senate as well as her being the presumed front-runner in 2024 if Biden did not seek reelection.[205]

So from my understanding she gets the final vote on split issues. She could have leveraged her political power to push these issues to get to vote.