I’m guessing what you’re after is the ‘stretches’ on the static page to be able to be sorted?
If so, you’ve setup the collection of streches which is great - but need to use a “collection list” on your static page to ‘link’ to this collection.
Upon dropping this in, click the drop down and link it to your ‘stretches’ collection, then style it as you like. Once done you can sort these, on the static page, by clicking on the wider collection (not an individual item) and following the tutorial to sort however you like.
Definitely a benefit in using the collections/CMS.
If nothing else the ability to sort, order and more easily add and edit collection items is huge, rather than having to copy/paste each individual items.
If you change styling on one collection item on that page, it is replicated over them all - again instead of having to change each individual static item. Saves (a lot of!) time and is really efficient to use the CMS and collections.
I guess the “CMS” page is intended to reference that specific CMS item or to be a template, as the name says.
I.e. your “Stretches CMS page” (not the static one) has the option to cycle through (up the top) each collection item (i.e. hip, glute, hamstring). This page should ideally be the information for each of these stretches/collections - not the collection overall (this is what the static page is for).
In short, the “CMS page” should be for the individual items in a collection, where as the static page is the overview - the place to show all of them.