I was studying Mandarin a few years ago and I was suggested to watch Taiwanese dramas since they tend to speak Mandarin and to also speak at a conversational level.
There's a lot of romantic comedies, so you can watch meteor garden, substitute princess, my queen, fated to love you, and I have found that all of these are very accessible to me as an American audience but I never got to the point where I could watch them without subtitles.
Another mostly Mandarin show that is definitely worth the watch is called nirvana in fire, and it is legitimately an amazing 40-hour long epic show that has sword fighting and wuxia and political intrigue and romantic subplots and a massive character list of all sorts of different people who all have their own thing going on all woven together into this amazing storytelling tapestry that rivals and in many ways bests anything that you can get in America or Western media.
But unless you're already very fluent in I'm not going to say just Mandarin but in the Chinese languages, you have to watch it with subtitles and it's definitely worth it.