400 is far too much. Just because you could follow 400 one day, doesn't mean you can do 400 everyday. That is a crazy number long term in 2020.
No real user is doing this. Twitter will know this, they will have marked your account. The ban may not come right away, but it will.
I think the best way to go is creating more and more accounts and grow them slowly.
For example instead of 1 account following 400 people per day make 2 of them following 200 people
BUT the problem with Twitter isnt the daily limits,bots,proxies etc
The MAIN problem is how to phone verify all these accounts.
If you run 100+ accounts this will be a real nightmare.
People will suggest to get free sim cards from companies.Well thats not possible in every country.
People will suggest even to buy these sim cards.I am affraid that these sim cards will not stay alive forever.
People will suggest verification services that for a small fee will verify your accounts,the problem is that most of them doesnt support voice verifications.
Even if they offer both SMS and voice verifications,charging $2 per verification looks a small fee but if your run 100+ accounts that can be HUGE
The best solution for phone verifications was Google Voice but it seems that doesnt work at the moment.Sad..
