github.com/crosire/reshade-shaders/blob/...ders/DisplayDepth.fx
That shader was added a while back and allows for viewing the depth buffer which you can then assign a hotkey for in ReShade's GUI to toggle on demand.
Some settings for the depth buffer might be needed in ReShade for certain games or game engines, logarithmic and inverted for example are popular in several newer games and for Unity engine ones there's a setting in ReShade for the depth buffer being upside down which is needed for correct depth display.
EDIT: Ah I'm being dumb, you mean a generic depth buffer as a sort of override for when ReShade can't properly hook the games actual depth for whatever reason, now I remember GeDoSaTo having something like that as a override for it's plugin system.
(Making depth instead of merely viewing.)