While Palpatine was hoping to use their connection against them, even he was unaware of just how powerful Rey and Kylo would be when they joined forces. With the former Supreme Leader shedding his Kylo Ren mask and moniker to revert to his true form of Ben Solo, he comes charging to Exegol to save Rey from her grandfather. Before he can get to her, however, he's ambushed by guards. Having tossed his Sith saber into the roaring ocean off the remains of the Death Star, Kylo (now Ben) is left without a weapon. Rey is able to use their Force dyad connection to hand Ben one of her two sabers (she was using Luke and Leia Skywalker's weapons) to save him.
Once Palpatine realizes he's dealing with a Force dyad between Rey and Ben, his plan for them changes. He syphons life from them both to restore his own ghostly figure to life, and their dyad proves so powerful that Palpatine is temporarily restored to almost Revenge of the Sith-levels of strength as he nearly wipes out the entire Resistance fleet. Fortunately for Rey and Ben, their dyad is also strong enough to keep them alive to destroy the Emperor. However, it takes Ben giving up the last of his strength in the Force to save Rey after she's finally struck down her grandfather. Their dyad is exactly what is needed to bring balance to the Force once and for all, but as Meaww points out, with Ben dying to save Rey, that link is gone forever.
But there is still hope here, as Rey is certainly still attuned to the Force. The closing scene of The Rise of Skywalker shows Rey taking on a new identity as she introduces herself as Rey Skywalker and raises a lightsaber previously unseen in Star Wars films: a yellow blade that finally gives her her own place in the Jedi Order.
