Start with ECMA-48 https://ecma-international.org/publications-and-standards/st...

Then find DEC and XTerm extensions https://invisible-island.net/xterm/ctlseqs/ctlseqs.html

I recommend starting with ECMA-35. The actual structure of escape sequences is explained there. Otherwise it gets lost that it's the ESC [ that is the entire escape sequence, an alternative form of CSI, and that this actually is one part of an entire mechanism of escape sequences with intermediate and final bytes. It's a control sequence that CSI then introduces.