Please refer below docs:
https://learn.microsoft.com/en-us/power-apps/chatbots?msclkid=2ae8e436cf9f11eca425b786063b5403
https://powerapps.microsoft.com/en-us/blog/power-apps-portals-introducing-power-virtual-agents-integration-using-chatbot-component-public-preview/?msclkid=2ae89a27cf9f11ec889999faa9c31693
Also refer:
https://www.bythedevs.com/post/add-an-ms-power-virtual-agent-to-a-canvas-app-in-power-apps-with-pcf