In Vim(and I assume Emacs too) it's also possible to just define keybindings for any sequence of inputs, allowing even mode changes inbetween and differentiating between different file formats.

I used that for a couple common symbols in LaTeX' math mode, e.g. entering ;lra gets me a \leftrightarrow.

But I wouldn't recommend that approach for multi-line snippets and more complex cases, the config will get unreadable otherwise.