While we're all advocating for our favorite science related YT channels, let me add a plug for "Physics Girl" (aka Dianna Cowern). Note that her channel isn't so much cosmology and deep theoretical stuff, but has a lot of focus on exploring "real world" aspects of science, including lots of field trips to see neat places and things, but explored from a physics perspective.

https://www.youtube.com/c/physicsgirl

Another great channel is Dr Becky (Becky Smethurst). Dr. Becky is an astrophysicist, so her channel is more specifically oriented towards astrophysics topics.

https://www.youtube.com/c/DrBecky