When you hit Play, the video streams through an adaptive format (HLS), and the resolver offers whichever quality tiers Instagram encoded the file in. If the original upload was compressed, that's the ceiling — no downloader can add detail that isn't in the source file.
Download for the best quality
The Download option links straight to the original uploaded file, so if you want the highest quality available, download rather than stream, then play it locally with any standard video player.
Why Reels sometimes look softer than Feed posts
Reels are optimized for fast mobile playback, so they're often compressed more aggressively than a standard Feed video. That compression happens on Instagram's end at upload time, not in the downloader — so a Reel and a Feed video of the same footage can end up at different quality levels.
If a quality switcher isn't showing up on the player page, it usually means the source only has one resolution available — there's nothing to switch between.