I had fun playing the scenario introducing the new gameplay additions but it is more the old good mechanics that is important and valuable. If you didn't like the core experience, this is not a gamechanger (in a way that Civ6 DLCs R&F and GS made the game much more complex and interesting). Buy it if you like playing scenarios more than you enjoy sandbox. I'd like to see a bigger, more fundamental DLC introducing a new futuristic era or more substantial global events (climate change, migration pressures).
I needed a second attempt to this game to fully appreciate it. My first attempt treated it like one of many economic simulators, where 'it's all economy, stupid'. Tropico 6 is however much more political than you'd expect from a game about dictatorship. The scenarios show the depth of the game and allow you to learn how the Tropican society works. Many reviewers complain about random requests from factions that you need to tend to - but splash screen advice fro the creators says - you do not have to meet most of the requests. It is an interesting game, teaching you that a good manger has to sometimes (often) say "no" - and in this sense it is brilliantly political. The sandbox playgame is a little bit uneventful and easy - but I have not yet tried it with the hardest settings.