Sure, if it were encoded at a variable rate. But then it wouldn’t be 320kbps CBR. Normally when I see people refer to 320kbps audio they literally mean constant bitrate. If it’s variable then for LAME mp3 people would specify V0 or V2. At least that’s the taxonomy that I absorbed when I was active on what.cd
Edit: you have edited your comment to remove mention of 320kbps so my comment is now moot :)