For 16 GB SSD with 4 GBs of RAM (which is what most Chromebooks used to be), you will need Debian with XFce, with 2 GB of swap partition. Nothing else will either fit, or work properly. I have given away 3 such laptops to friends with that setup (Arch might fit ok too, but because I was giving it to friends, Debian was easier to work with). After installing the v12 Bookworm Debian OS, with libreoffice, a couple of simple games (e.g. solitaire), Gimp, and that 2 gb swap partition, I was left with 5 GB free space. I had to occasionally do sudo apt autoremove to make sure the space wasn't eaten away, but overall, it stayed steady (dh -h will give you that info). With Trixie, you might end up with 4 GBs of free space, as it's bigger. Bookworm has updates until 2029.