This is a quick 'how-to' for setting items in the Quick Links web part on a modern SharePoint page - for example when provisioning team sites or upgrading existing sites to use the modern experience and migrating content from Promoted Links to Quick Links.
If you want to create Quick Link items from code, you'll need to understand the format of data that SharePoint is expecting when updating the web part properties. The easiest way to achieve this is add a Quick Links web part to the SharePoint workbench page (https://yourtenant.sharepoint.com/_layouts/15/workbench.aspx) and then click the Web part data button at the top of the page to see how that data is serialised in a modern page.