The advanced post selection allows users to query posts by specific authors. This field is a multi select field and you can select from multiple authors.
The posts query option exists in any of Unlimited Elements post widgets or product widgets for Elementor.
Step 1: Open the post query section in the settings
Step 2: Under Include By select author and then underneath “Include by Author” will show up.
Step 3: Under “Include By Author” add the author names you want to show up in your query.