lorian Soenens and graphic artist Rolf Neumann have teamed up for their first Mac app, IconMenu 1.0 (https://www.iconmenu.com), a search tool for icons. 

Accessed directly from the menubar, it allows you to directly search for and download icons and drag them in any app, in any format/size you need. IconMenu supports all available png sizes from 16px up to 1024px as well as svg and ICNS format.

It requires macOS 10.12 or higher. IconMenu costs $3.99; a demo is available for download.