I generate them: initially with my own generator (which is copyright an employer from > 15 years ago), on a later project I found that Doxygen can do do that for you out of the box :-)

For interactive discussion I just use Visual Studio's projection, for databases I use the SQL Server Management Tool ERD projector or pgAdmin if I'm using Postgres.

The point is that you're generating diagrams from code that's already been written, you're not modelling, do you? ;-)

Those are a different kind of diagram than the one you create from scratch to decide what goes in the program.