Lamp fitting wattages used to be important in the days of incandescent bulbs which put out a shitton of heat. If you put a 100w bulb in a 60w lamp, it would get very toasty in there and possibly melt or catch fire.
With LEDs its a bit more complicated. If you've got a lamp with a separate transformer putting out 12vdc, going over the W rating could end up burning out the transformer.
But I'm guessing this is probably a mains powered lamp you've got, in which case it's hard to give a good answer as the efficiency and heat output of different types of LED bulbs varies hugely. I would say that as long as the lamp is fairly open with space for air to circulate around the bulb then there should be no problem with it.
