ProductSearchSortField reference
This article provides reference material about ProductSearchSortField record.

Properties
Name
The field name.
Title
The field title.
Order
The sorting order.
Multiple values are allowed.
Example:
var titleSortField = new ProductSearchSortField(
	Name: "Title", 
	Title: null, 
	Order: ProductSearchSortOrders.Ascending | ProductSearchSortOrders.Descending);
var topSellingProductsSortField = new ProductSearchSortField(
	Name: "TopSelling", 
	Title: "The most popular products", 
	Order: ProductSearchSortOrders.Ascending);