Times New Roman, Arial, Courier New, Calibri, Cambria… all of these fonts are proprietary.

But there are open-source metrically-compatible alternatives to all of them, commonly included in Linux distributions and/or office suites like LibreOffice.

Probably the most popular set is https://en.wikipedia.org/wiki/Croscore_fonts, with Tinos, Arimo, Cousine, and in the extended set Carlito and Caladea. The former most popular set is probably https://en.wikipedia.org/wiki/Liberation_fonts, with Liberation {Serif, Sans, Mono}.

But a given system is definitely less likely to have a Calibri alternative than a Times New Roman alternative.

The Croscore fonts ARE the Liberation fonts, just renamed.

I keep both for naming compatibility and also because the 1.0 Liberation versions had truetype hinting (2.0 and up did not).