They have plug-ins for web tiles, and you can connect to the ArcGIS map services. It has a terminal, but I don’t use that function much. I generally do all data manipulation and prep using Python and postGIS, and use Q as a visualization and editing tool. But it has plugins for just about everything. Most of the data resources ESRI gives you is repackaged public data, so searching the internet will provide you with most of the layers you might need.
I don’t work in the architecture space, but a quick search gave me some guidance on how to integrate BIM models in QGIS. The 3D City Builder plug in might do what you need.