I have missing Calibri font in Pages. How can I download

Any font reference in an opened Word document in Pages must be physically installed on your Mac to avoid Pages warning you that it is missing and performing font substitution with a font that appears differently.

Calibri is a licensed Microsoft font and is only available from them per Barry's comments.

Calibri is a Microsoft font, and is the default font for MS Word documents.

It may be included with MS Word Mac, part of the MS Office Mac suite, or it may be available directly from Microsoft.

Regards,

Barry