How do I see the ID of a content type record?
When creating your entity reference field there is a "Mode" selection. The default is simple but you can choose to use a Views entity reference display type instead.

So in views if you create a new view (that displays the data you want) and add a entity reference display type to i. You can then use that in your entity reference field.

EDIT: Just seen the comment above referencing Show node IDs along with titles in Entity reference Autocomplete list Do that