https://www.freecodecamp.org/news/lightweight-linux-distributions-for-your-pc/

NameSiteComment
Puppy Linuxhttps://puppylinux-woof-ce.github.io/This tiny OS weighs in at under 300MB, so it can run smoothly even on systems with as little as 512MB of RAM.
Bodhi Linuxhttps://www.bodhilinux.com/System requirements are just 512MB of RAM and a 500MHz processor.
Peppermint OShttps://peppermintos.com/It only needs 512MB of RAM to run, so it will fly on that Pentium 4 machine or Core 2 Duo laptop you have stashed in your closet. While Peppermint OS is light on local resources, it integrates well with cloud and web apps. The OS builds in close integration with services like Dropbox, Google Drive, and more.
AntiXhttps://antixlinux.com/AntiX is designed to run on systems with as little as 64MB of RAM and a Pentium II processor.
Lubuntuhttps://lubuntu.me/Lubuntu will run smoothly on computers with as little as 512 MB of RAM and a 1 GHz processor.