I need to drill but have detected metal approx 3" x 3". Not pipes, not wires. Can I drill?
The short answer is No, you can't drill.
Drilling into masonry and hitting something unexpected can be dangerous and expensive.  That's why you scanned first, which was wise.  (No idea what you used to scan...)  Your scan found something, but you don't have enough information to know what with any confidence.  It could be nothing more than a scrap of metal that fell in the mix when the concrete was poured, it could be buried treasure, it could be something else that shocks, floods, or explodes.  Drilling into it is not the way to find out what it is.
There are other difficulties drilling through metal embedded in masonry but that's another matter.