Yes you can!
Stripe does allow for you to offer a partial refund. You will be able to follow the same steps as offering a full refund, and adjust the amount that is being refunded.
Find the full steps on issuing a refund here.
Remember, you can also issue a partial refund in Splash! Check out how in this helpful FAQ.
Additionally, when using Stripe, keep in mind that whether you're issuing a full or partial refund, Stripe's processing fee will not be refunded.
More information about refunds in general on Stripe here.