At what level can high school graduates go to university in Spain if they pass the DELE exam directly (that is, they do not need to study Spanish for 9 months in Spain)?

It mainly depends on your language level. If it is good, no problem, you don’t have to wait 9 months. If it is not, you will be called to study at some language schools (free). And if you are in high school and want to come to Spain, it seems that they need to do some tests on you before they decide whether to accept you or not. Moreover, the school seats are very tight now, especially for immigrants, so reservations must be made far in advance. It is also best not to come to a province like Catalonia, because it is bilingual, classes are taught in two languages, and you have to learn Catalan.

Wish you good luck