Hello @jonas.bloch, most symbols in the typst documentation have their LaTeX equivalent also available for queries.
If you type “langle” in the search box, it should pop up “sym”, see General Symbols – Typst Documentation
After, you can click on the symbol to get
$angle.l x angle.r$
should give you
P.S.: you can also take a look at https://detypify.quarticcat.com/, see this response by How can I more easily input unicode characters? - #2 by PgBiel