https://www.fidelity.com/viewpoints/personal-finance/college-529-spending
"While funds from a 529 account can be used to pay for expenses required for college, not all expenses qualify. Tuition and fees are considered required expenses and are allowed, but when it comes to room and board, the costs can't exceed the greater of the following 2 amounts:
- The allowance for room and board included in the school’s cost of attendance for federal financial aid calculations
- The actual amount charged if the student is living in housing operated by the educational institution
In other words, if your child is planning to live off campus in housing not owned or operated by the college, you can't claim expenses in excess of the school's estimates for room and board for attendance there. So it's important to confirm room and board costs with the school's financial aid office in advance so you know what to expect. Also, keep in mind that in order for room and board to qualify, your child must be enrolled half time or more."