Something useful that children can learn about emotions is that they have different strengths. Much of the time our emotions are so mild that we barely register them. We tend to only notice them when they get to an intensity that impacts on our thoughts and behaviour. And often, we tend to only focus on the negative emotions as their related thoughts and behaviours can be damaging. With emotional literacy, however, it's important to acknowledge positive emotions too.
Here is a spectrum of happiness.
This can be used with a child not only to show that emotions come in different strengths, but also to improve a child's emotional vocabulary (which on it's own have been proven to improve emotional intelligence). It also makes for pleasant discussions with you child if you can reflect upon a day, week, holiday or outing together and recount moments that made you feel different levels of happiness. Alternatively, you could list pleasant things that happened recently and take it in turns to point on the spectrum how happy each thing made you feel.