But Microsoft also still offers Visio Plan 1 and Plan 2 subscriptions, and those get you extra diagram styles for cross-functional flowcharts and swim-lane diagrams, shapes for network equipment ...

Visio in Microsoft 365 is a superb tool for creating custom diagrams to illustrate concepts that are difficult to explain through text. Here’s how to use it.

It would be worthwhile to label your rack in the same manner. My Visio rack diagram contains a sample 34U rack with objects from the custom stencil, as well as some Visio default items.