For a brief overview of how software engineering is done at Google, see my paper "Software Engineering at Google" <https://arxiv.org/abs/1702.01715>, and with regards to architecture, see in particular sections 2.9, 2 11, 3.3, 3.4, and 4.1.

We typically talk more about "design" than "architecture", so for example our architecture is typically documented in "Design Docs".