Is that possible to bake roughness, metallic and ambient occlusion into 1 texture map in blender so I can use it easily in unreal engine, as substance painter do?
No, you can't. Bake all textures into 3 files and then combine them in Gimp, Krita, Photoshop or Blender's compositor:
$\begingroup$ Thank you for the answer it was quite helpful. I searched using composite to mix these maps but unfortunately I couldn't find anything helpful, could you please help me and give me a tip on how to do that? $\endgroup$– RekanSep 29, 2022 at 13:40
$\begingroup$ This process is called channel-packing $\endgroup$ Sep 29, 2022 at 15:40