1.Would you like something to drink?
不定式to drink为后置定语,修饰宾语something.
2.Come and have something to drink.
不定式to drink为后置定语,修饰宾语something.
此题的have为行为动词,相当于drink.
如果解释为“有”,句意不通；
如果解释为使役动词“使/让”,则它后面的宾语补足语是不会用带to的不定式的.