Unfortunately %formats reflects the libraries more than the formats, especially for fonts.

The $Imager::formats{tt} entry reflects availability of freetype 1.x, which no modern system should be using. Modern systems should be using Freetype 2.x, which is reflected in the $Imager::formats{ft2} key.

To enable that when installing Imager itself, you will need to ensure Freetype 2.x and its development headers are installed, this is included with Strawberry perl, and packaged by most Unix-likes (Linux, BSDs, etc).

If you want to declare a dependency you can depend on Imager::Font::FT2 which will only successfully install if Freetype 2.x is found.

Some Linux distributions package Imager (Fedora, Debian, Mageia) which might simplify things for you if you're using the system perl.