Can I download the latest Safari

Safari is updated to the latest version when you update the iOS on your iPhone. See: Update your iPhone, iPad, or iPod touch - Apple Support

You posted your question in iPhone space. You might want to switch to Mac community space and ask your question there. And when you do that, include more details such as what exactly iMac 21.5" model you own and what is the current macOS version on it as those things matter.

Oh... And don't post using capital letters only. Such practice is considered to be rude.

CAN I DOWN THE LATEST SAFARI ON MY IMAC 21.5/

DOWNLOAD NOT DOWN