This link shows the top-voted questions:
In a New Year's spirit, how can I restrict this query to top-voted questions posed in the year 2021?
When searching on the site you can restrict the search to posts created in some date range using
created:2021. You can also search only for question if you use
is:q. If you sort by votes you get this as a result. (You can use
is:a to get the answers posted in the given range.) And of course, you can add other restrictions, just as in any search. For example, you can restrict this to one specific tag or you can use
intags:mine to display only questions in your watched (favorite) tags. See also advanced search and help center.
Alternatively, you could use SEDE. Here is a query showing questions, answers and all posts. (SEDE is only updated once a week, so the data for the whole year will be available after this Sunday.) SEDE also has a table PostWithDeleted, which has some information about deleted posts. But deleted posts are unlikely to get among the top voted questions. Here is the same query restricted to deleted posts. (It goes without saying that these queries can be modified and improved in many different ways. E.g., you can add restrictions by tag, look at the posts of a specific user, etc. It is also possible to create queries that look at all sites in the network: top questions, top questions excluding SO.) As a bonus, I will add a query showing hot network questions from this year and a query showing bounties from this year. (And I will also remind that such questions are listed also in this chatroom.)
I should probably add one important caveat - the posts made in 2021 are still gaining votes after that. The searches and queries mentioned above look at the total score - that includes also votes cast after 2021.
Using SEDE, it is possible to look at votes cast in 2021 rather than posts created in 2021. Here are the top questions and top answers. We can see from those queries that there are also some older posts which are still getting a lot of votes. If you want to have a look at posts before 2021 with most votes from this calendar year: questions, answers.
It goes without saying that you can change parameters in the searches and in those SEDE queries to look at other years or completely different timespans.