These are two feature-length "episodes" (Original Video Animations) that summarize the series from a different perspective:
This follows the complete story of Light Yagami and the detective L, adapting the original 12-volume manga series. how many death note episodes are there
If you are looking for Death Note content outside the 37-episode anime, be aware that the episode counts change drastically depending on the medium. Where to Watch The anime covers the entirety
The introduction of Near and Mello and the final resolution. Where to Watch the main narrative is complete.
The anime covers the entirety of the original manga storyline by Tsugumi Ohba and Takeshi Obata. The story has a definitive beginning, middle, and end within those 37 episodes. While the manga received a one-shot special chapter years later (which the anime did not adapt), the main narrative is complete.