RenderTarget2D output depth Data?

I wanted to export the data with depth z to png via RenderTarget2D, which I did via this function, but I found that it had been normalized internally beforehand, which was not what I expected, because I didn’t know what the maximum depth of the scene was before normalization, so I couldn’t process the exported image correctly.

After checking, I found that the engine actually has a built-in conversion function from DepthStencil to FLinearColor (ConvertRawD32S8DataToFColor(Width, Height, In, SrcPitch, Out, InFlags);), but I couldn’t find the required PF_DepthStencil’s Format in RenderTarget2D.

When I try to find the metadata to convert it myself, I find that the engine is not open to me.

Is there any way to fetch the unconverted metadata, or to fetch the depth value before normalization?