If you have an inactive Twitter account and want to keep it then you will need to log into Twitter or the account will be removed.
Twitter has announced that it will be removing inactive accounts that have not logged in within the last six months from the 11th of December 2019. You can see an official comment that Twitter gave to The Verge below.
“As part of our commitment to serve the public conversation, we’re working to clean up inactive accounts to present more accurate, credible information people can trust across Twitter. Part of this effort is encouraging people to actively log-in and use Twitter when they register an account, as stated in our inactive accounts policy,”
So if you have an inactive Twitter account that you would like to keep it is recommended that you login to the account.
Source The Verge