The Copilot integrated with Microsoft 365 doesn’t have a model switcher it just is what it is. You are talking about a completely different product that Microsoft calls the same names.
I'll say it for the third time: "in VSCode". There's no ambiguity about which Copilot that is.
VSCode Copilot or Copilot Chat?
imo, any VSCode user needs both extensions: "GitHub Copilot" for inline completions, and "GitHub Copilot Chat" for interactive, multi-turn coding chat/agent.