There are a number of respected options here on the Fractal Forum. First, the factory presets are very good. If you take a look at them you will see many techniques that you can use in your own presets. A lot of effort has been put into them. Many Fractal adoptees find a lot of information and value just in the box. Which is great, because they're free.
However, there are also a number of aftermarket products that are well regarded. Here are some to look up on the Forum and/or Youtube and the Interwebs:
@2112 - Leon Todd (his Fractal Forum handle is 2112) has a lot of free videos, as well as heavier presets with Mesa Boogie patches. Leon Todd is a bit of a Legend on the internet as well as on this forum with great videos that include examples and instruction. It's well worth looking up Leon's content.
@Cooper Carter - Cooper Carter has produced a master class video that explains in detail how to get the most out of all Fractal platforms. You pay to access Cooper's videos. You can find free videos that cover much of the same ground, but Cooper Carter's master class is really useful if you want systematic training on how to use your Fractal product. It is helpful to know that Cooper is affiliated with Fractal and has worked with many high profile artists (Neil Schon is one that comes to mind, but there are others) helping them design presets for their live rigs.
@austinbuddy - Austin Buddy is another person who has presets for sale.
@simeon - Simeon has contributed a lot of individual block examples that are very well regarded on the forum.
You can also look up Fractal Audio "Gifts of Tone". This is a series of presets that Fractal has released over the last two Christmases from well know Fractal Audio customers. They are a free Christmas gift from Fractal.
@York Audio - York Audio is a professional touring guitarist and Fractal Forum member who has produced a number of well liked IR packs.
There are other members who have produced a lot of content. Some folks to look up -
@Moke - builds great presets; shares many of them in Axe Exchange
@fremen - long time forum member who shares some free presets, as well as some paid presets
@yek - Yek has produced some excellent PDF files with in depth information on amps and fuzz/overdrive/distortion pedals. These PDF files are professional quality that Yek has shared for for free. The PDF files are extremely well done, though they are currently missing some recent additions that were released in the latest firmware updates.
There are other folks who sell presets that are not coming to mind. If you're new to Fractal, and modeling in general, you can't go wrong with looking up Leon Todd's videos on YouTube or with signing up for Cooper Carter's Master Class. If you want something systematic, comprehensive, and well produced, you can't go wrong with Cooper's material. Of course, the necessary interwebs disclaimer applies, IMHO and YMMV. Perhaps others can add more regarding folks that I haven't included in this post.