When it comes to the display of DynamicWidgets the first thing the engine will do is look at the renderingContent parameter. It will then look through the Dynamic Widgets children looking for a matching attribute regardless of the order the child appears in the list of children. If an attribute match is not found on one of the children it will use the fallbackComponent to display that attribute. Here's a screenshot of the renderingContent (Facet Display) settings for this index as seen in the dashboard.
In this example CodeSandBox you can see how it keeps the order of the attributes inline with renderingContent by rendering brand first even though the refinementList which has the attribute brand is the last child component. You'll also see the menuSelect fallbackComponent is used for those attributes who's components are commented out.
You can also see the refinementList with the attribute="popularity" is not rendered because popularity is not set with renderingContent. This leads us to how you can customize the DynamicWidgets. First if you wanted to simply display refinementLists for all of the attributes in renderingContent you could set fallbackComponent={RefinementList} and pass no children to DynamicWidgets.
However you would be better served by setting the widgets you would like for the corresponding attributes as children of DynamicWidgets and setting your default Facet Display you want on most pages, more on this in our Facet Display guide. You can include child widgets with attributes not in your default Facet Display in Dynamic Widgets. They won't appear unless the default Facet Display is changed which leads us to the true customization Merchandising Facets.
Using rules you can merchandise your facets, meaning you can change the facets available and their order based on a number of possible trigger conditions set in the rule. For example if you are using category pages you could set a rule to trigger when a user navigates to a particular category page changing the attributes for Facet Display. This will override your default display causing DynamicWidgets to look for children with matching attributes or use the fallbackComponent if none are found and render in the order given by the rule.