There is a superb book for children about coronavirus and the pandemic, covering lockdowns and all sorts of great topics here. Even if you don’t want to purchase the book, you can use the “Take a Look Inside” link on that page. Switch the view to full screen view and read it on screen together with your child.
NSW Health has resources for children, with videos about covid-19, a fact sheet about supporting your child if they need a covid test, and a downloadable photo-story-booklet for children to prepare them for a covid test. There are also short videos of children getting answers from doctors about covid-related questions.