There is more to that. He had a successor called Carrero Blanco, but the guy got yeeted by ETA (Basque nationalists) a few years before he died. If you look up the Spanish Space project, Carrero Blanco was the first one to join.

After Franco died, even if the government tried to keep things orderly everything was in shambles since they knew they couldn't maintain the whole thing up without a figurehead like Franco. Seeing the writing on the wall, the high commanding generals of the army contacted the exiled political parties and handed over a deal: accept our terms and we will allow you to have democracy. And everyone agreed except the Basque. These conditions were things like no persecution of military personnel for past charges, the unity of the territory of Spain and that the county has a king.

And maybe you don't know, but a few years after democracy came there was an attempted coup d'etat carried out by a man named Antonio Tejero. The army took to the streets bu the king pleaded to them to go back to their bases and so they did.