We’ve been using the Bespoke Shipping App. Excellent support, appears to
handle every shipping service in existence and works very well with many
options to get the pricing just right. And it adds metafields to Shopify
to handle volumetric shipping.
Fields which, of course, Shopify needed to add years ago and standardize
for all customers and shopify app as they all currently do “it” differently
and if you move from one app to another, you’ll need to get all you
dimensions re-added to work with any other app.