Im also curious. Im currently having to put together a large system design document together and am struggling to find any solid automation tools.

The most productive tool I've found is: https://github.com/terraform-docs/terraform-docs

Otherwise there is a lot of cloud, K8s, and then microservices + app design (typescript)

Decent:

https://github.com/bafolts/tplant

https://github.com/TypeStrong/typedoc

IntelliJ IDEA can generate diagrams of e.g. call chains or class inheritance structures: https://www.jetbrains.com/help/idea/class-diagram.html