Hi Pankaj,
Thank you for contacting Syncfusion support.
At present we do not have support for “Compressing existing PDF document in ASP.NET Core platform”. We have already logged a feature request for this. Currently we do not have any immediate plans to implement this feature. We will let you know when this feature is implemented. The status of implementation can be tracked through our Features Management System:
Please let us know if you have any concerns on this.
Regards,
Sowmiya L