For local customers only, yes you can! You can update your meal plan to be a mix of vegan/meat protein by clicking Account in the head, followed by "Meal Plan" (linked) on the left.
From there, click "Change Plan" to the right side of "Meal Deliveries".
From there, you'll see the words Quick Picks and Custom. To do a mixture of vegan/meat, select Custom. Then click edit to the right-hand side of the delivery cycle you want to modify (Early Week or End of Week, like opting into one or both of those); you can create a combination of meat and vegan on the following page.
On the Edit page - scroll down to find the meat options and select the quantity of meat protein meals you'd like. Make sure to click 'Save' by 11:59pm PST Thursday prior to the week you want the plan updated.
After creating a custom meal plan, to view what you'd be charged for the upcoming week, you can head to Upcoming > Charges. To see what the upcoming items would be in your deliveries, head to Upcoming > Deliveries and you can swap items there if there are items you don't prefer!