To elaborate on the other reply (which is correct):

FAFSA computes an "expected family contribution" amount which it uses to judge eligibility for aid (particularly grant-based aid). Parents are expected to contribute 12% of their "discretionary net worth" to that amount. Dependent students are expected to contribute 20% of their total net worth to the family's expected contribution. This is where the advice to keep college savings out of the student's names comes from. (I pulled those percentages from here: https://fsapartners.ed.gov/sites/default/files/attachments/2020-08/2122EFCFormulaGuide.pdf)

However, most 529 accounts are owned by the parents. The child is just the "beneficiary". So FAFSA treats 529 accounts just like bank accounts, general investment accounts, and any other non-retirement account.

More significantly: your income has a bigger effect on your expected financial contribution than your assets. In order to build a large enough college fund that it can disqualify your child from receiving grant-based financial aid, you realistically need an income which alone is high enough to disqualify your child from receiving that aid.