Hello @Anonymous,
I hope you're doing well. Unfortunately, there's no single source for reliable SPICE models. The best sources continue to be manufacturers who take the time to accurately model their parts. Most manufacturer's however don't produce plain SPICE files but rather usually support a specific proprietary flavor of SPICE and usually some conversion process is required. This is an area we want to address in the near future, to make it easy for you to create your own models without having to dig into the SPICE syntax.
Once you have a suitable model, you can easily assign it to a component on your schematic by right-clicking on a component and selecting the ADD model option.
Let me know if there's anything else I can do for you.
Best Regards,
Jorge Garcia
Product Support Specialist for Fusion 360 and EAGLE
Kudos are much appreciated if the information I have shared is helpful to you and/or others.
Did this resolve your issue? Please accept it "As a Solution" so others may benefit from it.