It shouldn't affect battery life because drawing energy from a cold lithium ion battery doesn't cause harm. It's charging quickly while cold that can be bad for the battery and that's why Teslas reduce regen to a safe level in that situation.
That's my understanding too. (I'm not a battery expert by any means though!) Also max power will be limited by a cold battery, but again you're not going to harm a modern S3XY Tesla from it, the car will protect itself.
That said, by preheating
with wall power you will avoid a bit of extra cycle wear on the battery. That may have been
@MikeHolliday's point, and that is real, even if the actual long-term battery health effect is likely lost in the noise for any given car/battery. I wouldn't stress at all about this. Anyone who can plug in easily every night should do so, but if you can't, don't stress at all, the car will take care of itself. The only thing to avoid is parking overnight in the cold with very low battery level. Give her a charge before a cold bedtime!
Preheating
without wall power isn't going to avoid any cycle wear though, as far as I know. If anything, I expect it will use overall more energy from the battery than just not preheating - therefore more cycle wear. But again, I wouldn't stress about this difference so long as you're able to park with a solid charge. If you like driving a preheated car, just do it, even if you can't leave it on a plug overnight.
Also, from what I've seen - not consistent data, just lots of anecdotes - time age is typically a bigger factor than cycle wear on Tesla NCA batteries, unless they've gone through excessively stressful events e.g. very deep discharge. (No idea if LFP might be different, I know it's said to maintain capacity better.) Your battery is going to degrade no matter what. Use it however works best for you and enjoy the car. Plug in whenever it's convenient, but when it's not, don't stress about it, just maintain a decent charge in the cold overnight and you're solid.