While the labia are not as sensitive as the clit, there are a lot of very enjoyable ways you can pleasure and stimulate them. Slowly rubbing them up and down like can bring them close to orgasm without them climaxing, which makes for great foreplay. Do not forget that lube will make stroking the labia feel so much more pleasurable for her.
Many vulva owners can become really sensitive after climaxing from clitoral stimulation. It may even become painful for them if you touch it immediately, so you will want to hold off further stimulation for a few minutes. This makes the labia the perfect option for focusing on until that clitoris calms down and returns to normal sensitivity. If the labia are long enough, you can also rub the clitoris through them if it is too sensitive for direct stimulation.
@shadeyontop If I left you with some questions, let me know!