Hi Lucas,
#Regarding how we can set a default page
size on the document editor
You can use setDefaultSectionFormat API to set the default section
format. You can change the required SectionFormatProperties default value.
To know more please refer the below
documentation.
https://ej2.syncfusion.com/vue/documentation/document-editor/how-to/set-default-format-in-document-editor/#set-the-default-section-format
#Regarding what's the "metric"
used for these values( px, cm, inches? )
The metric used for these values are point.
Please let us know if you need any
further assistance.
Regards,
Ajithamarl