Investing for my young son. Right now just have money in VTSAX in a personal brokerage account for him. Should I switch to a different account type for tax advantages, etc?

Saving for when he’s 18. Also considering a Child Roth IRA in addition to what I have now/whatever is recommended to me here. I do not want a 529 or any type of college savings type account.

Edit: Apparently my 4 year old needs earned income to be eligible for a custodial Roth IRA. This seems ridiculous to me but ok.