I’ve thought about this a lot, and I think the age of majority should be 21 years old and the age of consent should be 25 years old.
18 is too young to be legally an “adult”; they’re still in high school most of the time. I think 21 is a better age; they are in their 20s, so not a “teenager” or a “child”. At that age you can sign up for the military, join the police force, or become a firefighter. Handle your own finances, sign a lease, etc.
I think 21 is good for the age of consent as well because if you are adult enough to join the military then you are old enough consent to sex with anyone above the age of 21.
The more sheltered you are growing up, the less experiences you have to learn and grow from, and I would say that having the lack of experience to challenge the status quo generally is good for society.