One of the cool examples is about universal transitions between icons through transparency, scaling and blur. And no lottie is needed.
I was always sure that the CSS property will-change was needed only for optimization on slow computers. It turned out that it helps the browser transfer the load to the video card, and it renders the first frames of animation better on any device.
Jakub Krechel writes a lot on animation on his website and shows examples (mostly with the Motion library). I recommend!