copy numbers from messages
In case of receiving code; using SMS, iMessage; like bank authorization code, 2F auth, etc. it is not possible to copy number.
Especially if the number has from 6 to 9 digits iOS predict this number like phone number and context menu allows to copy number is not available. by the click on iPhone to initiate voice call.
12.1(15B92)
iPhone 8, iOS 12.1