Hi Derek,
Greetings from Syncfusion.
Currently we do not have support to increase the size of the CheckBox, we have already considered it to be a feature request, and it can be tracked through our feedback portal below.
Please cast your vote to make it count. We will prioritize the features every release based on the demands and we do not have immediate plan to implement this feature since we committed with already planned work. So, this feature will be available any of our upcoming release.
If you have any more specification/suggestions to the feature request, you can add it as a comment in the portal.
Regards,
Hemalatha M.