The Google algorithm update for 2021 aims to provide a holistic image of the user experience. This means that the better it is for your rankings, the more you follow all of the criteria. It will provide a better experience for your website visitors.
To my knowledge, Google has not announced any major updates in 2021. The last major update was last year, with a specific focus on COVID related searches. That said, focus on content, relevance and quality, and you can't go wrong.
There is no official announcement for the Google algorithm update in 2021 BUT you should focus on Core Web Vitals (website loading speed) this year because Google has announced last year (2020) that Core Web Vitals will be the strongest ranking signal in 2021. So focus on that. For more information on Google update, you can read this: Google Algorithm Facts and Latest Updates That Every SEO Should Know