3rd Party Age Verification

I would like to add an age verification to the checkout. Are their any examples of where this has been used with draw raffle ticket sales and where would I find details of how I can add it? 

You can use some plugins

• https://sf.digital/squarespace-age-popup
• or free code on Codepen, then we can convert it to SS https://codepen.io/jonbp1993/pen/woKVbr