[wren6991]

It's a numbers game. Sentence complexity within a given novel follows a distribution, and if you keep reading then you'll keep getting some input that is at exactly the right level for you to grow. It's normal to stumble on the exposition at the start of a chapter and then breeze through the dialogue.

I did find it helpful early on to go through web novels with a low 95% coverage vocabulary count, like the Narou stories indexed here: http://wiki.wareya.moe/Narou

Natively is a great resource too. It does Elo-style ranking of novel difficulty: https://learnnatively.com/browse/jpn/?language=jpn&lvl=

I highly recommend real stories over generated text and synthetic exercises, because the key to success is staying engaged long term. Stories are just more fun. Also get yourself a reading setup that minimises the pain of dictionary lookups, because there are going to be a lot of them. ttsu reader + yomitan is excellent.