How would I write a sequel to a story I read

You could write it any way you want to but it is important to keep similar aspects the same. Such as the main characters name and attitude. Most sequels have new characters and different conflicts. You would need to make sure that your idea would be different but still similar to the first book. If you need inspiration read summarys or fan made stories of sequels to books and movies. The plot is usually much different from the original book or movie in a sequel sometimes characters die or new problems are caused and solved.

Explanation:

Don't just pick up where the last story left off.

Give the reader something new.

Make the stakes different.

Play with Expectations.

Include at least one great new character.

Don't be afraid to let beloved characters go.

Identify what made the first book special, then offer more.