And I would add that things like Peter Pan's Flight.. if the 5-year-old knows what peter Pan is.. or Pooh, etc.. can get long lines with lots of kiddies in the parks in the summer. Not sure
Not sure how tall the 5-year-old is.. but 7 dwarves is a roller coaster-type ride that is well within the average height for a 5-year-old. And that can get a long line too.. the thing about Genie plus is that is far more restrictive than the old (and free) FastPass system.
You will need to look up RECENT videos on use of Genie Plus and Lightning Lane to gauge its value and your ability or willingness to utilize it. I had seen something recently about a lacked cheat-sheet card for cast members controlling the lines about how many LL guests to let through to how many STANDBY guests depending on ride and whether it is peak time or off-peak, etc. Cannot seem to find it now.. but it was enlightening.
There are 7 attractions at
Magic Kingdom with height requirements:
Height Requirements at Magic Kingdom