Sort products by newest
By default, all products are sorted by Position in category.
Also using native magento 2 functionality, you can sort products by attributes. To add sorting option by attribute, you need enable option Used for Sorting in Product Listing on product attribute edit page.
For sort products by adding date (or update date) with Improved Sorting Magento 2 Extension, you should add new Date Ranking Factor and then create Sort Criteria with this factor.