Irish Passport Photo Question - Los Angeles

Hello,

I am applying for Irish citizenship for my children who qualify from the grandmother who was born in Ireland. The application for foreign registry requires for photos of the child two of which have to be signed by a witness. Since they have to be signed, I assume these must be physical passport photos. However, US passport photos are a different size and all of the passport photo places around me only do the US size.

Do I have to take a photo and have it it printed and try to cut it to exact size myself? Seems like a silly question, but I am not sure what to do here.

Thank you