Can we turn this question ("How do I upgrade Ubuntu 18.04 to 21.04 on i386 architecture?") into something like "I have a 32 bit computer running Ubuntu 18.04, and want to use an operating system with recent versions of packages. What all options do I have?"
That question would not be strictly about Ubuntu, but it would help Ubuntu users continue using their 32 bit computers with a supported operating system.
People still ask questions like "How to install 32 bit 18.04?" Since 18.04 would go EOL in another two years, can we have a generic question with possible migration options?