to convert a 32 bit linear acescg to 8 bit with the view transform "baked" you need two ocio nodes:
Open the exr
Go to 32-bit Preview
Check Display transform is set to OCIO Display Transform, Exposure = 0, Gamma = 1 (this is just a display transform that matches render view)
create two nodes:
Add OCIO Adjustment: Source: ACES - ACEScg; Destination: Output - sRGB
Add OCIO Adjustment: Source: Utility - Curve -sRGB; Destination: ACES - ACES 2065-1
Set the display transform in 32 bit preview to 'ICC Display Transform' - this is what the image will look like when you convert it to 8bit and should match the render view
convert format to rgb/8 -> Document -> Convert Format/ICC profile -> RGB/8 from drop down.
credit to this post:
https://forum.affinity.serif.com/index.php?/topic/129188-cant-export-aces-12-ocio-what-i-see-in-32-bit-preview/&do=findComment&comment=729666