Why not just using the LibreCAD manual? It is linked on the forum start page.
See
https://librecad.readthedocs.io/en/latest/ref/tools.html?highlight=command for command line commands.
There is also a short-cut section, you can use the manuals search function to locate it.
I think there is also a commands table in the wiki, it has its own search function too.
The tool option bar content is dynamic. It depends on the active tool and when no tool is activated, the tool option bar is empty.
So best is to activate a tool, e.g. Angle Line and then toggle the tool option bar. Then you can easy locate it and move it to your needs. Usually it appears above the drawing area.
The tool option bar for Angle Line contains Angle, Length and Snap Point fields.
investing less than half an hour into Search function can save hours or days of waiting for a solution