I don’t know if I’m missunderstanding something…
The important thing is, Twitter allows you to create tweet to another users (if the user gives you access).
If you read here: https://dev.twitter.com/ads/reference/post/accounts/%3Aaccount_id/tweet, how to post a tweet, you can see that you also can use “as_user_id” parameter to select the user, so, in concordance to this, twitter ads api allows you to preview a tweet with an specific user.
This may be helpfull for you