I have two twelves I don't know much about them, or there power needs as it was a gift. My question is will my Celica handle a 2000 watt amp it has a bigger battery like one found on a truck .

As long as your alternator is healthy you should be ok. May want to consider the use of a capacitor to help as well.

There is a small cylinder with a fuse in the cable that goes from the battery to the amp can that be a capacitor ? The car had the connections when I bought it. Just no subs or amp

That would be an inline fuse.

Do you happen to know the purpose of it? And thank you for taking ur time to help me out

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Just like a fuse for anything else, it cuts power if amperage exceeds the rating of the fuse.

You will have to find out the brand of the subwoofers and the amplifier. Many brands, especially cheap ones, market their stuff with MAX wattage which is pretty much useless.
What's the amperage on your battery? What gauge is your wire? Have you upgraded the stock wiring from the alternator to the battery?

Also, don't buy a capacitor, biggest waste of money.

Should be able to find info on the two subwoofers as far as wattage at whatever Ohm, go by RMS and not peak. What brand and model are they?