I have not been in Berlin for Silvester so I can't recommend any place as such.
Which is why I never posted a reply.
But since no one else is answering and you are buellering us......
When I was in the Waldorf Astoria Berlin a few weeks ago, I noticed that they had some New Year Specials.
A 6 course dinner in Les Solistes with champagne in the Library on 15. floor at midnight.
Or a two night stay with the 6 course dinner included.
You would have a very good view of the fireworks from high up in the WA.
The link takes you to a page showing the restaurant options in the WA.
Look under 'specials', click the 'info' button, choose English and scroll down to the New Years offers.
These offers will certainly give you the opportunity to dress up.
https://www.menumodo.com/app.php/hot...1024&tags=null