Quick Tutorial for a 360°-3D setting in Blender 2.9

Camera in position – Center of the view

Render Properties

Render Engine Cycles

OutPut Properties

Stereoscopy / Stereo 3D

Choose Stereo Mode and Top-Bottom

Select Camera

Object Data Properties

Lens Panoramic

Panorama Type Equirectangular

Stereoscopy

Spherical Stereo

Ready to render

Resolution

A final resolution of 4096×4096 est enough for VR devices

Each image is so at 4096×2048

F12

When the rendering is finished it appears like a anaglyph image.

But when saved

It shows properly