Hi,
Are you talking about modeling custom threads or are you talking about choosing to actually model the threads of
a bolt/screw/hole in a design?
There are a number of ways to create threads for custom designs but if it is for a standard thread then usually there is
simply a checkbox to actually create or to simulate the threads. The reason for this is that threads are computationally
expensive and most people will either turn the threads off or just use a simple joint and put into the drawing notes
that a certain fastener is used.
This is the Hole command.


Or you can make the hole and use the thread command.


Both of these methods use Standard thread types. If you want Custom thread types then there is an App in the
Appstore.

One of these is written by one of the regulars in the forum. I apologise I cannot remember who or which one at the
moment.
Failing all these you can create threads using the various tool in fusion like Coil and modify what it gives you.

Or you can sweep a profile.
As an engineer I would suggest that Standard threads exist for a reason and will always be cheaper but there are
always times when custom is the way to go. Hope this has helped.
Cheers
Andrew