I still don't know what role a calendar widget can play on the website. What's more, the default calendar widget of WordPress is too simple. It only displays the date of the article published in the current month. If you want to see other months, you can directly jump out of the current page. Here is an Ajax Archive Calendar, a calendar widget plug-in. You can view the date of the article published in the year and month through Ajax without refreshing.
After installing the plug-in, enter the gadget page and add the "Ajax Archive calendar" gadget to the sidebar.