Assuming you mean the connections between the components - a hodge-podge of different models, tools, techniques. There is no one way to do it, partly because of how different any given system can be from another. Even within software engineering, it really depends on the industry you're in, the application of the software, the stakeholders, the risks.
But generally speaking, most people only track the connections at design time, as an artifact of overall architecture. And this isn't great, because as the system changes (modern software systems change constantly) the entire system development lifecycle is not being re-assessed every time some component changes.
So in the best case, with a Waterfall model, you have very well defined connections in design, and you have to pray that your SDLC validates that design. But most people prefer Agile, which in practice means "I don't need a well defined system! #YOLOEngineering". So everything is built ad-hoc and nobody even attempts to figure out the entire picture. And in that case, Operations may be told to figure it out (they're the ones running it all, so they have the best vantage), and they tend to implement monitoring and distributed tracing that enables cobbling together a picture of how things are actually working. But that's not fed back into teams' designs, it's just used for addressing problems after the fact.
To be specific: you might use ADRs and manually crafted diagrams to map out the connections, or UML, or some other systems diagramming tool/standard. But often that's created only at a certain level of the system, and doesn't dive deep into component interfaces or tolerances/limits or availability. So the full picture can never be seen from one view, and it's almost never the teams themselves mapping it out.