SQL Server Management Studio still has no dark mode, although there is a hidden one that Microsoft really doesn’t want you to use (I think you need to change a registry flag, also it sucks). But I think Azure Data Studio might.
Personally I’ve been using lot of dbeaver for my database needs (mysql, oracle, postgress, apache drill, sqlite) which has a dark mode.
It should also work with sql server, but I’m not sure if is it’s missing some of the tools people need 🤔
Never heard of dbeaver, but I use JetBrains DataGrip 99% of the time, which looks the same as every other JB IDE (not bad). There are some super clunky but occasionally useful SQL Server tools in SSMS but for typical dev work there’s nothing you really need.