ProtoPie for Figma - Add powerful, conditional interactions to your Figma designs
Textures.com - Textures.com is a website that offers digital pictures of all sorts of materials.
LottieFiles for Figma - Insert Lottie animations as GIFs and SVG's into your designs
Poly Haven - Poly Haven (formerly known as Texture Haven) is an online website where you will find scanned textures without any cost and that are of high quality.
Pexels for Figma - Insert beautiful photos from Pexels into your designs.
Poliigon - A library of materials, and HDR's for artists including free textures that want photorealism.