Convert vtf to icns

Download and install the latest version of Filestar.
Right click on one or more Vtf file(s) on your desktop and select Convert with Filestar.
Type convert to icns in the search box.
Press Convert.

What is the difference between .vtf and .icns?

Name: Valve Texture Format; macOS Icon Resource File
Extension: .vtf; .icns
Format: Binary; Binary
Category: Raster Image; Developer
Developer: Apple
Description: It is an icon image file used to show application icons in the macOS Finder and macOS dock. It contains one or several .PNG images and it supports 1bit and 8-bit alpha channels.
MIME Type: image/vnd.valve.source.texture; image/x-icns
Sample: sample.vtf
Wikipedia: .icns on Wikipedia