Thank you for contacting Syncfusion support.
Based on provided information we have analyzed your requirement “Calendar dates contains the icon which has event in a date”. Currently we don’t have a support for special dates. But your requirement can be achieved by using OnMonthCellLoadedEvent. Also we have prepared simple sample for the same. Kindly refer the sample from following link,
We hope that this helps you, kindly revert us if you have any concern.