Employee directory implementation in sharepoint online

Refer below links

Creating and configuring: https://en.share-gate.com/blog/corporate-directory-sharepoint-search

Adding New Properties : https://www.premierpointsolutions.com/training/help-and-how-to-articles/how-to-show-the-fax-number-in-people-search-results-in-sharepoint-2010/

Full Demo: https://www.youtube.com/watch?v=bl4NGWneFpQ