All recipes say to cook broccoli first for broccoli rice casserole, but i want it to be more crunchy. Will it not just cook enough when it bakes?

Or, you could cook them separately.
Make the rice casserole sans broccoli, roast the broccoli to desired crispness, and top the casserole with it.

Do you have a specific recipe you're following that I can help you decipher?

Yes, the recipes recommend to cook the broccoli first so that it's cooked-through and not raw (it won't cook through entirely amidst all that rice in the casserole). Maybe, if you still want the brocc to have some bite, you can cut it into smaller pieces than the recipe recommends and then add it raw to the casserole. But I worry that doing nothing to change the broccoli and adding it raw to the other ingredients will result in unpleasantly raw vegetables pieces among creamy rice.