From Digimon to That Time I got Reincarnated as a Slime, isekai is a genre of anime that holds a lot of staying power in the industry. The topic taker should research:
The beginning of the genre
What made it popular
Its impact on the anime industry
Is the animation of isekai not to the same standard of other anime, or just drawn in simpler styles? Does the numerous amounts of isekai better or worsen working conditions for anime artists?
What genres do isekai cross over with?
Why is isekai so popular?
Are there too many isekai?
Will isekai bring about new genres of anime?
By researching these aspects of isekai, the topic taker should be able to get a full picture of the how, what, and why of isekai. The topic taker is, as always, free to do more research on isekai, such as whether or not isekai helps its viewers by increasing positivity in their mood, help them relax from the stressors in life, and so on.