I shoot in HLG3 on my Sony camera in bt 2020 color mode, and want to convert it to rec 709, can you tell me the best project settings for it? Here's how I've set it up, thanks in advance.
right click on your media, make sure its color space is set to HLG. Then just set your view transform in project settings to Rec 709. That should do the trick. If not, the view transform you have selected in the pic above should work.
If the generic transforms in Vegas are problematic, you should be able to get a proprietary LUT from Sony for your camera and shooting format. There are also third party LUTS available, some great, some so-so.
The best LUT I know if for doing this is Leeming LUT. It is not just a transform but accurately converts the colors for use in Rec 709 based on charts shot on a Sony a7III. It has saved me so much time with color correction. Just be sure to follow the camera setup instructions carefully for HLG 3. leeminglutpro.com/
You want to render to an ordinary Rec 709 limited video (assuming you're outputting a normal format like AVC) so players will work with it properly.