Are employers with a self-funded or level-funded plan required to offer coverage to spouses and/or children? Does the answer change depending on the size of the group?

No, self-funded plans do not have to offer coverage to spouses or to children. That is an employer decision (though some carriers/administrators may not allow dependents to be excluded from coverage).

Applicable large employers who purchase a self-funded plan must offer coverage to dependents (defined as children) or could face a penalty under the employer mandate.