May i ask, do you happen to know where to find for loop examples i could use to practice for arduino?
I think that you are confusing what happens in the body of the loop with the for statement itself.
A for loop, as you can see from your examples, just says "Do this until some condition is met, starting with these initial conditions, and doing that after each iteration".
What happens inside the loop is as simple or as complex as you can make it.
The key is knowing how/where to use the loop index inside the loop, and how not to use it. Generally, modifying the loop index inside the loop requires extreme care.