When my son was 18, he got his job. I know way late. We didn't know what we were doing as parents. I tell every parent of young children to start your kids earning money around the house as soon as you can and have them work outside of the house for someone else by at least age 16.
Anyway, I had caught on to the power of the Roth IRA brokerage at that time and I told him that whatever money he made at his job, I would match it (up to the Roth annual contribution limit) and we would open up a Roth IRA brokerage and transfer the money into that brokerage and if he wasn't interested in learning about investing at that time, I would just invest it for him. I ended up investing it in $TSLA. A year later, I did the same thing with my daughter. Over the last 4 years I have contributed $19k to my daughter's Roth. About a month ago, her Roth IRA brokerage value was $100k. With a conservative rate of return of 7% in 35 years when she is my age, she will have $1.2M. And that assumes she never decides to contribute to it herself.