A large-area, deep-field survey of the Universe can help reveal both of their natures, with gravitational lensing allowing the construction of dark matter maps and galaxy clustering revealing our expansion history.
With only the first 1% of its data available for release, the ESA’s Euclid mission is the first new-generation mission attempting to measure these great cosmic unknowns. Here’s the impressive “page 1” of its results.
https://bigthink.com/starts-with-a-bang/euclid-page-1-of-cosmic-story/