As a Lightweight Render Pipeline design decision, Post-Processing Stack v2 Ambient Occlusion does not work in LWRP. (Because it uses compute shader)
So I made a custom post-processing stack v2 effect to force rendering AO.
Add Custom/LWRP Ambient Occlusion
to your post-processing profile.
And configure built-in AO.
- It only works for MSVO.