You really need to show them at 2 or 3, certainly by 3, that they need to listen to their parent/ caregiver. They learn where the lines are by realising when they've pushed things too far. When there are no natural consequences the child can kearn from, the parent has to be the one who provides the way to impress upon the child that they should have listened.
You're not going to succeed in getting your child to listen to you if you leave it too long after 3.
They are not babies. They are capable of learning habits that are explicitly taught to them. The habit of eating with a spoon or fork, the habit of using the loo, the habit of helping tidy up, the habit of sitting at the table while eating and drinking, the habit of saying please/ thank you, the habit of being gentle with the family pet...
You also need to make sure your child isn't hungry, sick, tired, or upset about something, and that your daily lives are suited to the sort of child you are dealing with - some children are happy to potter around home all day and some require a good deal of physical activity. There's a context to everything.
It's important for parents to teach and encourage their children to express their feelings verbally, and to show their children that they too have feelings. I'm not advocating authoritarian parenting. It's important to apologize to children if a parent feels they were immoderate in showing irritation, or unreasonable in expectations, or impatient. This teaches the child that we can try to fix mistakes, and we can acknowledge the feelings our behaviour causes in other people, as well as honoring the relationship and repairing it.
Children need to be learning by age 3 that there are expectations of their behaviour and that these expectations are going to be consistently required, by a parent who is on top of things and in control of herself or himself.