Habit stacking is a term coined by Lyndsey Hookway, describing a method to introduce new settling methods (and phase out unsustainable ones). I speak to many people about this when they are keen to move away from feeding to sleep or relying solely on feeding for settling (though huge caveat - feeding to sleep is normal, healthy, and for many people the easiest, most peaceful way to help baby find sleep. Nothing wrong with it at all, unless it's a problem for you).
The basic idea is that when you want to change something, rather than just taking something familiar away, you start by layering on additional sleep associations - eg patting, shhhing, singing, humming or cuddling.
Choose one or two things that baby seems to like, and which feels more sustainable to you. (Pro tip: when considering settling methods, always think "would this be sustainable with an 18 month old?" - so I'd advise against intentionally introducing rocking or bouncing) then start to do them during your daytime feed to sleep and (when you have the energy and enthusiasm) during night feeds too.
After a few weeks, once this new habit is bedded in, you can begin to experiment with removing the less sustainable thing (in this example, feeding), but keep up the other soothing methods you've introduced. You might experiment with responding to night wakes initially using the new technique, and see how baby responds.
Sometimes they might be reassured and settle (if perhaps they were just seeking some comfort to help them into their next sleep cycle), sometimes they might make it clear that it's a feed they want (maybe they are hungry, thirsty, or in pain, in which case a pat on the bum and a shhhh is really not going to meet their need!)
This is real trial and error stuff. Sometimes baby will go for it, sometimes not. You might find that if you wait another few weeks, they'll respond differently.
It takes time, and effort, and commitment to do this but many people who really want to make a change but want to do it gently find this a useful route.
Have you tried habit stacking? How did it go?