"Grand scale" refers to something that is vast, extensive, or large in size or scope. It often implies an impressive or magnificent level of magnitude or proportion. Full definition
Later, he went looking for a larger space where he could work in grand scale making paintings with random patches of thin paint. (brooklynrail.org)
For an artist who usually works at such grand scale, gallery exhibitions usually offer intimate and serene affairs that give the audience an opportunity to experience the work firsthand. (artspeak.nyc)
Develop a regular daily writing routine, especially when your project is on as grand a scale as writing a book. (authorhouse.net)