Yes. Donors can cover the platform fee when donating via a CrowdRaiser, provided the option has been enabled on the related cause.
OrgHQ administrators can control whether donors are offered the option to cover the platform fee for donations to your cause, including donations made through CrowdRaiser pages. This is set in the cause's donation form settings. See How do I customise my donation form?
When this option is active, donors will see a toggle allowing them to cover the platform fee or remove it from their donation total.