Previews for Toy Story 4 usually last around 5 to 10 minutes. However, this can differ based on the cinema and any special promotions or sneak peeks included.
The Roanoke Island horror story is mysterious because not only did the settlers disappear without a trace, but also the only clue, the word 'Croatoan', is very ambiguous. We don't know if it was a destination, a warning, or something else entirely. And there were no signs of violence or natural disasters that could explain their vanishing.
You can usually find story previews on the official websites of authors or publishers. Sometimes, they are also available on online bookstores or reading platforms.
The length of the previews before Toy Story 4 can vary. Sometimes they might be around 10-15 minutes, but it really depends on the theater and the specific screening.
You usually can find story previews in the menus or homepages of the relevant platforms. Just look for sections labeled 'Previews' or something similar.