As the others have said, a cone is easily made and a flat pattern generated in Inventor Sheet Metal. However there are a couple of things to watch out for. The model requires a rip (small gap) somewhere so that it can actually separate and lay flat. You can produce this using the sheet metal Rip tool, or simply model your cone as a rotation through 359.9°. The other thing is that the thickness of your part matters-- if you just want to produce a paper flat pattern, then set your "sheet metal" thickness to the paper thickness; if you're producing a thicker model, but need a paper pattern, then the sheet metal rule for the part needs its K-factor set to 1 instead of the default 0.44 (K-factor is the neutral surface of a bend, no stretching or compressing, expressed as a number between 0 and 1).
Hope this helps. If not, ask again and attach a part file of your attempt.
Sam B
Inventor Pro 2021.1 | Windows 10 Home 2004
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