aa-globe

This plugin has no settings. 
Just activate the plugin and check if sold out items have moved to the bottom of the list.

Catalog Sorting by Stock Status – In Stock First, Sold Out Last

This plugin changes the sorting of a catalog (or product category) so that out-of-stock items are always at the end of the list

Inbound Horizons

Cliff

Bulk Sort Attributes for WooCommerce is a WooCommerce extension that allows you to bulk 
order WooCommerce attributes by ID, Name, or Name (Numeric). When there are 
hundreds or even dozens of items in an attribute it becomes tedious and time 
consuming to sort by hand. This plugin makes it an easy task!

Bulk Sort Attributes for WooCommerce

Bulk sort WooCommerce attributes when they are too numerous for custom sorting by hand.

Catalog Sorting by Stock Status – In Stock First, Sold Out Last vs Bulk Sort Attributes for WooCommerce