I am sure it is true that a Mississippi 8th grader died. However, it is rare that these things happen. The article is using a real instance for propaganda to push the narrative that children are just as vulnerable as older populations, and to scare people into masking and getting vaccinated.
Anecdotal stories lead people to think that the frequency of these occurrences is normal. Media/government know this, and this strategy is successful a lot of the time.