Too much red cabbage leftover!

I love this cabbage and rice pilaf. You can easily double the cabbage.
https://unwrittenrecipes.com/blog/2017/small-victories-best-rice-pilaf-with-roasted-red-cabbage-famous-fridays

You can use your leftover cabbage in making fried rice -- a great way to use up leftover rice along with odds and ends of vegetables. Here is a Food52 recipe for fried rice with some cabbage in it: https://food52.com/recipes/66947-stir-fried-rice-with-leftovers

There is a Food52 recipe for crispy sheet pan rice, here, https://food52.com/blog/23455-easy-dinner-recipes-best-rice-recipe-with-bacon-fast, that uses cabbage. (Basically a baked sheet pan version of fried rice that you can put your leftover cabbage into, using rice and whatever vegetables that you want.)

In addition to Miss_Karen's ideas, 3 more for what to do with the extra cabbage you have now:
1) Simply saute some or all. This will reduce volume and increase flavor. Then freeze in usable portions for future dishes (freezes well).
2) Sauté grain, cabbage & onions in butter or other flavorful fat. With buckwheat, this is called Kasha Varnishkes. I forget what it's called when you use short pasta. All are delicious. Eat as is, or add garnishes to taste - sour cream, poached egg, a bit of leftover meat.
3) Make soup. Many varieties and co-conspirators work well with the cabbage - beets, potatoes, fish.

Most grocery stores will cut the head of cabbage in half for you if you ask. I mix about a handful into my chicken wild rice soup. Saute it with the onions and celery. Then puree it before you add the chicken & rice. I also use some in my Oriental meatballs. (You can make the meatballs and then freeze them...) you might consider getting a bagged version of shredded cabbage it's a smaller quantity.