Yes and no. If you grade your 10-bit footage as 10-bit, then produce an 8-bit POST render, THAT render will be better than the reduced (8-bit) original. Most of all because the final render can be done with a much more powerful processor and sufficiently high bitrate (for example, I produce my footage as 8-bit H264 at 150 Mb/s). During the final render process, the resulting gamut is re-mapped into 8-bits. While my TV (65" 4K LG OLED) is able to display 10-bit H265 and HDR, I thus far stayed away from producing output that way. Just so costly (processing time). In order to convince myself that it is worth doing it, I will take some of my best footage and use the Adobe Media Encoder to generate the final H265/10-bit output. I hope it'll be worth the hours of processing...
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M2P "NORMAL" mode is recorded in 8-bit. However, the video processing done from the sensor to that render is 10-bit and it shows a significant improvement in color and natural texture (as long as shot in standard or 1,0,0 to avoid over-sharpening). But, by all means, DlogM-10bit post processed is way better.