Current Twitter limits
Direct Messages (daily): The limit is 500 messages sent per day.
Tweets: 2,400 per day. The daily update limit is further broken down into smaller limits for semi-hourly intervals. Retweets are counted as Tweets.
Changes to account email: 4 per hour.
Following (daily): The technical follow limit is 400 per day. Please note that this is a technical account limit only, and there are additional rules prohibiting aggressive following behavior.
Following (account-based): Once an account is following 5,000 other accounts, additional follow attempts are limited by account-specific ratios.
Ref.: https://help.twitter.com/en/rules-and-policies/twitter-limits
I mean, if you are doing over 2,400 Tweets per day, you really need to get a life.
The real intent of these limits however is to stop all the bots and spam. Before Musk took over and when Trump was on the platform, there would be thousands of nasty replies to every Trump Tweet within seconds of posting, almost all of them sent by bots.