Salesforce DX - How enable org shape?

The Org Shape feature is in pilot status as of Winter 18.

It is not yet generally available and cannot be enabled on "off-the-shelf" Dev Hubs. My understanding is that the feature is only enabled in orgs that are created as part of the org shape pilot.

It has entered Beta as of Winter 21. Still not production, but it should be available to all

https://releasenotes.docs.salesforce.com/en-us/winter21/release-notes/rn_scratch_orgs_shape.htm