I think there's a lot of grey area for what "style" is, but e.g. formatting and what not is pretty easy and not-contentious in my experience. Most people want consistency more than they want their way.
How I did it as part of a ~35 person dev team was adopt one of the popular ones from the community (e.g. Google's) - treat it as a benevolent dictator. Apply it to the entire code base in one giant shot (disrupting any pull requests that were in flight but fixing them proactively), then enforce it with tooling. Leave the door open to anyone who disagrees with the defaults. It's on them to propose the change with rationale then put it to a quick majority vote with a subset of the team. I think 2 things have actually changed since the very beginning (line length from 80 -> 120 and something else that I don't remember right now).
When something changes, making a sweeping change is part of accepting it - if it's too risky/disruptive then it has to be very valuable to do.
How I did it as part of a ~35 person dev team was adopt one of the popular ones from the community (e.g. Google's) - treat it as a benevolent dictator. Apply it to the entire code base in one giant shot (disrupting any pull requests that were in flight but fixing them proactively), then enforce it with tooling. Leave the door open to anyone who disagrees with the defaults. It's on them to propose the change with rationale then put it to a quick majority vote with a subset of the team. I think 2 things have actually changed since the very beginning (line length from 80 -> 120 and something else that I don't remember right now).
When something changes, making a sweeping change is part of accepting it - if it's too risky/disruptive then it has to be very valuable to do.