Dylan can't be 18. For evidence check out the Sophia/Dylan part 1 when they talk about Dylan's upcoming birthday.
Dylan says - " I'm going be ** not 7 ".. or something like that..
Which clearly means he's turning 17 not 7. Lol
I don't care about Dylan's age.
He first appeared with the face of someone who had just graduated from elementary school.
At the same time, he is in the 11th or 12th grade of high school.
(If I understand correctly, Ellie is in 12th grade and Dylan is in 11th grade, but I'm not sure.)
He received sex education from his mother that was difficult for even a 12-year-old to receive, and he drank at nightclubs that were difficult for even 19-year-olds to enter.
The reason I said "I don't know how old the developer set Dylan's age" was because of the inconsistencies in his behavior.