I think the conical tips are for soldering surface mount components which are tiny.
No, they're hopeless for SMD stuff. Once you get much smaller than 0805 it's all about surface tension and persuading solder blobs to go where you want, rather than applying solder to individual joints the way you do with through-hole parts. A bevel tip (or concave bevel) is much better for drag soldering fine pitch IC legs than a conical.
Also, you don't buy the ubiquitous <£10 mains-powered soldering iron with a conical tip to work on SMD parts. Not unless you're a) desperate b) naive or c) wildly optimistic. (I did try soldering some 0603 resistors using one of these, with lead free solder for extra masochism, just to see if I could do it. The answer was yes, but it wasn't pretty and it's not an experience I want to repeat in a hurry.)