I'll do the dishes after dinner.

饭后我会清洗餐具

You must do the dishes.

你必须洗餐具。

You can say do the dishes or wash the dishes.

你可以说清洗餐具或者清洁餐具。

The kids offered to do the dishes.

孩子们主动要求洗盘子。

Let me do the dishes.

我来洗碗吧。

Could you please do the dishes?

请你洗一下餐具好吗？