Yes. If it's a global block, your alt account will be permanently blocked.

Its a infinite block on one fandom. will I still be banned?

Yes. But just on that fandom.

Keep in mind that making alt accounts to get around your block will make it harder to appeal on your main, because along with the original block reason, you also usually have to elaborate on your sockpuppeting.

I use two accounts interchangly but not because I'm blocked somewhere. It's because this account (Otterlett) Is set up on a school-issued computer. Last summer, I had to turn it in and didn't have access to my fandom account for almost 3 months. The day before I had to turn it in, I talked with the bureaucrats of the wikis I'm on and they gave me the green light.

Even though I have my computer back, my parents are kinda strict and make me put my chromebook away when I'm not using it for school. That's where my second account comes in.