If you have Nintendo Switch Online, then I can't recommend enough that you to play and complete Super Metroid before you start Dread.

Super Metroid is one of my all-time favorite games and is probably that which I've played through the most times in my 30ish years of gaming. With one notable and minor exception, it (in my opinion) holds up fantastically and still handles more satisfyingly than any other game in the genre that it birthed. It has excellent replay value, too, since it's possible (albeit difficult) to play all but its final area totally out of order and with skipping certain power-ups.

Also, its atmosphere, music, and story remain unparalleled to me in their uniqueness. Beyond its introductory sequence, its entire narrative is wordless and communicated exclusively through gameplay. Relative to, say, an RPG, its plot is threadbare but all the more powerful when it does hit, which is why I'd suggest playing it rather than reading a summary of it (either online or assumedly at Dread's beginning).

It's also a rather short game and can be completed in a few hours if you've even a little experience with Metroidvanias and knowledge of how their progression systems work.

In short: if you're gonna play just one Metroid game before Dread, make it Super. If you do complete Super and are hungry for more before Dread, then I'd also recommend Fusion and Zero Mission (both on the Game Boy Advance) in that order. Fusion is Super's somewhat controversial sequel whereas Zero Mission is a remake of the first game without its foibles. In my opinion, both are great games. In my opinion, Fusion is a great story follow-up to Super despite its breaks from tradition, which are thematically appropriate in-game.