Is there a way to repeat and loop the material within the clip to fit the length of the clip?
It is possible by using Fusion.
On the edit page, place the Fusion composition clip on the timeline and adjust the length of the Fusion composition clip.
Select a Fusion composition to open the Fusion page
Drag the material (footage) to be played from the media pool onto the node editor.
Connect added nodes
Open the inspector of the material (footage) node and check "Loop"
If you stretch the time of a Fusion composition clip, the stretched time will be black.
Open the Fusion composition clip in the Fusion page, open the inspector of the source (footage) node, uncheck/check "Loop" and check it again. This resets Fusio's looping keyframe information so that it plays properly.
♯ iteration loop ♯ time remap