Carbo loading is generally recommended for endurance events - anything longer than 90 minutes at a moderate pace. In addition, carbo-loading typically has to be done several days in advance. It's possible to glean benefits from carbo-loading the day before, but only if you've been actively maintaining your glycogen stores by replenishing them after excercising.
Basically, a 5k run isn't long enough to use up your glycogen stores unless you're really not getting enough carbs in your diet, so the carbo-loading is kind of pointless. It also depends on the type of foods that you're using for your carbohydrates. Grains can negatively impact your performance, especially wheat glutens which create inflammation.
The general recommendation for eating before a 5k is simply to eat a good meal 3-4 hours before the event. Something with complex-carbohydrates - e.g. fruit and whole grains - not simple carbs like sugar, as this can spike your insulin levels and make you sluggish.
If you wanted to feel what it's like to run out of glycogen during a run, I'd suggest doing a 20k (or half-marathon). Without carbo-loading beforehand, you'll likely deplete your energy stores and enter a state of low blood-sugar (aka "hitting the wall") about 15km or 90 minutes into it.
Over time, endurance training increases the amount of glycogen that your body can store, so you can run longer before hitting the wall, as long as your glycogen stores are full.