Gonna give too much answer:

Arch is an "Install what you want" distro - the base installation is quite minimal (eg. No gui by default), and the defaults mostly follow upstream - so there isn't much inherent heft.

If you pick light software it stays light, if you install bulky stuff, it gets bulky.

That said installing most of the major binary package distros (eg. Debian, Rocky) with the same package selections will be of similar size and runtime bulk. There are exceptions, eg. Nix is probably an unsuitable choice on a machine like a Chromebook with small storage because its package managent model keeps a lot more stuff around to enable some neat flexibility/compatibility tricks. Likewise, distros that depend heavily on Snaps or Flatpacks (eg. Silverblue, increasingly Ubuntu) will tend to use more disc space and have some runtime penalty that will be more noticeable on a low end machine.

Arch is "rolling" model, so they track current upstream fairly closely and just upgrade indefinitely. This means things are always fresh but change when they change, some other distros, like Suse Tumbleweed are similar. Stepped release distros like Debian Stable or Rocky try to keep things as consistent as possible for the support period of the release (but upgrading from release to release is likely to be more of a hassle).

There used to be some Chromebook specific distros like GalliumOS that carried patches for the common issues and pre-selected suitable weight packages, but as things got upstreamed they became unnecessary and died out.