Even when I say and show the name of something my child likes, they don't imitate the word. Is there a way to build vocabulary without trying to make them say it?

Even without imitating and saying it, they may be listening and understanding, or responding with expressions and gestures. Add a short word like "car" or "it's dirty" to what your child is looking at, and try waiting a little without demanding a reply. When they respond with a point, a glance, or a sound, take that as one turn of the conversation. Rather than making it a condition of "say it and I'll give it to you," the basic approach is to repeat usable words within enjoyable exchanges.