ManyPixels is a design company that provides vetted designers for a flat monthly fee. They also offer 2,500+ illustrations and 2,000+ icons. All are royalty-free and available for instant download.
Illustrations XYZ is a curated directory of free vector and illustrations websites. The site features many valuable resources and has a search engine and filters by format' function for easy navigation.
Libraries for Everyone
Illustration libraries for everyone is a Figma plugin that allows you to insert high-quality illustrations right into Figma. Just drag and drop to add it to Figma. All the illustrations are released under a creative commons license.
Scale by Flexiple
Scale by Flexiple offers 200+ high-quality open-source royalty-free vector illustrations for commercial use and with no attribution. You can also change the colors before downloading them as .svg or .png files.
Designstripe allows you to create beautiful illustrations with no design skills using a library of customizable illustrations, a simple online editor, variations for every object, and sliders to adjust visuals.