In addition to what topo said, I'd strongly recommend listening to artists specifically renowned for their songwriting and/or composition, whether or not they're in a similar genre to the one you're writing in. I'm sure you'll already have your own preferences to explore, so there's little point in me reeling off a list here, but if you're stuck, try some Stevie Wonder, Quincy Jones, Sting, Pat Metheny, Joni Mitchell, Brotherly (much less known than the other but great all the same - try System), Brian Wilson/The Beach Boys, The Beatles or Steely Dan. They're all amazing.
If you're thinking about developing specific ideas, the first port of call is always to listen to what you have written so far "in the third person" (as it were) and consider what you, as listener, want to hear next. I always find that the best cure for writer's block is listening to new music (i.e. that I haven't heard before). This helps me (to use a slightly cringy phrase) keep a fertile imagination and keep thinking in terms of the sounds I want to hear and feel rather than technical devices and theory.
Ultimately, this is a very personal question, and you need to invest a little time in experimenting with your compositional process and finding what works for you.
Composition, in my experience, is less about having ideas than developing them. I'd recommend studying a little Baroque music for this purpose - the way Bach, in particular, developed (at times) incredibly simple motifs into such spectacular, beautiful and complex music beggars belief. Mozart was also exceptionally good at this sort of thing (obviously not Baroque, but still). Try listening to Bach's first two violin partitas when you get the time. If one particular movement catches your ear, learn it (on whatever instrument) and its Double if it has one. As you get to know the piece, you'll begin to notice links between passages you had thought to be new material - any one phrase (except the first few bars of some movements) is usually derived from previously heard material. Once you get to know the music and the style, it becomes more like an organic stream of consciousness than anything contrived. To this end, it may help to consider composition more like slowed-down, refined improvisation (and vice-versa) than some sort of auditory equivalent of a novel. When you hear what people like Bach could create from such small beginnings, it's easier to hold your own initial ideas in higher esteem and concentrate on how you develop them (and that involves being, in a sense, subservient to them yourself).
As far as successfully executing dizzying about-turns like you describe is concerned, Jacob Collier's album is (imho) about as good as it gets.
Sorry for the wall of text. Hope I've helped a little.