I have found that Portra is definitely the pastel type film. On 160 portra, if I want that look, I shoot it at 100 and develop normally. I shoot 400 at 200 for the look. 800 is nice for pushing but haven't had very much experience with it, shot like 1 roll only and I under exposed it (1600). As far as scan, it seems that Silverfast software and negative lab pro get it right. Haven't tried vuescan. Epson software is inconsistent on color shifting.
I haven't tried adjusting developing times with the 160 or 400 as I was happy with the results shooting it the above speeds. It gave a nice subtle desaturated look. I suppose the pastel look would be elevated, slightly more over exposed.
For what it's worth, the film has a lot of latitude. I just shot some fall colors metered at box speed to get a richer color. It is a really fantastic film, very flexible. Wonderful skin tones on anyone. I shoot primarily 35mm, Nikon F2 with non metering prism. I have always metered the film with a hand held meter.
Keep in mind, a lot of the you tube hipsters are doing the majority of this in post. Nothing wrong with that but it is not where you should start. I prefer getting it from the emulsion. You can figure this out in short order using a 35mm camera. Take notes, adjust your ISO's on a roll. 9 frames at box, 9 frames -1 stop, 9 frames -2, etc.... develop normally or just send it out with no instruction. It should answer your questions. If your still not happy with the look, send off another similar roll and tell them to pull it a stop ....