Try Stephen Sondheim's stuff. David Bowie didn't call him the Shakespeare of musicals for nothing.
He wrote beautiful, intellegient, challenging musicals for grown ups.
You might be familiar with Sweeney Todd - there was a Tim Burton adaptation of it with Johnny Depp - or Disney's adaptation of Into The Woods with Meryl Streep, Depp and other Hollywood celebrities... but both of them are truncated to fit the short running time of a film, and that kills most of the clever rhymes/pacing.
Pacific Overtures is my favourite - a musical about 18th century Japanese economics 🤣 (it's about the Americanisation of imperial Japan).
There's a fantastic song written in haiku where a brothel madam attempts to teach new sex workers about sex positions, a song where the Emperor's advisor sings about trying to assassinate his boss through 3 minutes of insane internal rhyme schemes, and a haunting string peice in which a samauri husband and wife bid farewell to one other before he is executed - both parts are sung by male actors, as they would be in a traditional japanese Kabuki theatre performance.
The big setpeice, a song called Someone In A Tree, follows an elderly man reminiscing about the time when he was a little boy who climbed a tree outside a government building and overheard a treaty being drawn up between European, American and Japanese officials. It deals with the foibles of human memory and how our perception of events can be distorted by time.
you could also check out Sunday In The Park With George - a musical based on the life of French painter Georges Seurat, which deals with the obsessive, addictive nature of being an artist and features a copy of a Seurat painting that literally 'comes to life'. There's a recent filmed production with Jake Gyllenhall, plus the original Broadway production with Bernadette Peters.
A lot of his shows are hard work, but rewarding if you enjoy witty rhymes. A Little Night Music, Company and Follies are great too - Follies was produced by the National Theatre in 2017 and they screened it in cinemas, if you can get hold of a copy of that, it's a fantastic show about middle age and the regrets that come along with aging (not recommended if you're feeling depressed)
Hope that helps!