Trying to help my elderly mother. I think this is a Hanger Bolts not sure the size?

I think when I go to a home improvement store I need to ask the person for 4 of these hanger bolts and the hanger bolt driver. Not sure of the size or anything else, but I think that goes into our power drill, right? It's for a dining room chair.

https://preview.redd.it/etmq5wh9oi4g1.jpg?width=480&format=pjpg&auto=webp&s=ebae155cb1093abbfc6107f5b62d70d9d0ffa80f

https://preview.redd.it/iy7q5cqcoi4g1.jpg?width=480&format=pjpg&auto=webp&s=ad030f69a94834733f50fea97c92694a4f88da7c