You are NOT entitled to overtime if you work over 8 hours in a day. While that is the law in a few states it is not Federal law and it is not the law in Ohio.
You ARE entitled to overtime if you work more than 40 hours in a week. That is mandatory under both Federal and state law.
Nothing in either Federal or Ohio law requires that an employer pay a premium rate for working on holidays. Nothing in either Federal or Ohio law requires an employer to provide paid holidays.
If you WORKED over 40 hours in a holiday week you are entitled to overtime, but because you worked over 40 hours in a week, not because of anything to do with the holiday.
If, on the other hand, you had the holiday off (with pay) and worked (as an example) 35 hours over the rest of the week, you are only entitled to be paid for 43 hours at straight time, not at overtime rates. You only get overtime when you WORK more than 40 hours in the week. If you are getting paid for time you did not actually work (holidays, sick time, vacation, personal time) the employer is not obligated to consider that as time WORKED for purposes of overtime.
In other words, you get paid OT based on how many hours you WORKED, not on how many hours you got paid for.