Last time I looked (admittedly, years ago), most resources seemed to be in the vein of "here's Fortran 1990, and once you've learned that here are a few chapters on F03 and F08, treated separately".
It'd be great to learn there exists a "Fortran: the good parts" sort of thing that just completely elides the outdated stuff.
https://fortran-lang.org/en/learn/
BTW, the Fortran Lang website (https://fortran-lang.org/) is THE official website of modern Fortran, maintained by the modern Fortran community.
You may also take a look at the modern Fortran discourse at
https://fortran-lang.discourse.group/
where you can find all the gurus of modern Fortran. They are very willing to help if you post a question. I have asked all my Fortran questions over there during the development of PRIMA.
Also https://fortran-lang.org/en/ is a good hub to find more information, packages, etc.