You'd create a web standard for categorizing cookies (required, performance, login/session, metrics, etc). Meta tags? Naming scheme? .well-known? Lots of ways to do it.
If the website conforms to the standard, then the browser could use its own UI to ask the user for their preference. Importantly, the user would be able to state global preferences like: "only required and login cookies, don't ask about others", and then they wouldn't need to be prompted by every new site. If the website doesn't conform, then they'd need custom UI to comply with existing cookie laws, same a today.
So, the website could lie and say that their tracking cookies are in the required category, but they can do that already by not using a cookie banner, or miscategorizing the cookie in the banner.
I think the users who hate cookie banners and the sites that don't want custom cookie banner UI would like this approach. Sites desperate to trick users into allowing tracking cookies: they'll still find a dark pattern and we'll hate them for it.
Then people will converge on implementation patterns that couple the tracking cookie to a necessary cookie. You cannot keep one without opening the door to the other.
An easy compromise is for the default behavior to be to drop cookies when the session ends and to disallow third-party cookies. That gets you most of the privacy benefits while breaking a low percentage of sites.
