It's very tricky for a simple enough reason: the Crips and Bloods aren't overarching organizations like the Five Families/Patriarcas/DeCavalcantes, Winter Hill Gang, or the modern Mafia incarnations in Italy. They're loosely affiliated organizations made up of local "cliques" or "sets" that cooperate somewhat when it benefits them but are mostly autonomous. Most modern gangs are structured this way: MS-13, Calle 18, and most others that could be named work similarly. Efforts to unite these cliques into a real structure have to date been unsuccessful. The most organized ones left are probably the Latin Kings, and even they aren't truly analogous to what groups like the Italian Mafia used to be. The RICO Act and decades of all-out war by the FBI (along with, in the case of the Mob, some spectacularly bad leaders of whom John Gotti was the main one and gentrification/integration of Italian Americans) and every other federal law enforcement agency have been very successful at stamping out the centralized model of organized crime.
If you want an all-out war, you'd need to find a way to unite them into real organizations first. That's very tricky, but it might be possible. You'd need a few charismatic and capable leaders and some sort of force or reason to bring them together. There is actually a somewhat interesting possibility: the FBI in conjunction with those leaders makes it happen. This would be modeled on what they did in Boston in terms of literally creating Whitey Bulger and the Winter Hill Gang to fight the Patriarcas, who they in turn successfully marginalized to become the main organized crime unit in New England (and brought the FBI along for the ride). Here's my idea. For whatever reason (maybe a super anti-drug politician comes to power and starts the Mexican or Colombian Drug Wars early), the Latin American cartels go completely insane and start a massive war on level with what we saw in Mexico in the late 2000s that spills over heavily into the United States. Narcoterrorism is a big feature, and after a series of spectacular gangland slayings cum terrorist attacks, eliminating them becomes the U.S. government's number one priority. At this point, some corrupt FBI agents similar to H. Paul Rico/John Connelly/John Morris and the dozens of others in the FBI who created the Winter Hill Gang decide that maybe turning the relatively more docile, seemingly less threatening black street gangs into a national organization to counter the infinitely more savage (supposedly) Latino gangs would be in the net interest of U.S. public safety. It's the same argument that was used in the Boston FBI, with Winter Hill/the Irish Mob being the blacks and the Mafia being the Latinos. Working with capable leaders of either the Crips and the Bloods, they turn them successfully into a national organization and turn a blind eye to their activities. The other side, seeing this happening and now having a real reason to unite (or be marginalized, with the incumbent possibility of being violently dispatched), does it similarly in an organic way, but with more hiccups. Namely, recalcitrant local set leaders are assassinated. They expand their power steadily with the FBI institutionally turning a blind eye and forces in it actively helping one side, whose leaders are top echelon informants and use the relationship like Whitey Bulger did to dispatch rivals who become problematic.
Eventually, inevitably, after a couple decades of full court press the Latino cartels are defeated like the Medellin were. Within half a decade of this point, people start noticing what a menace the super Crips and Bloods now are. Eventually, through a whistleblower, leak, indictment, or lawsuit, it becomes public knowledge that the leaders of the side the FBI actively aided are working with them and profited from the relationship to do in their rivals. This causes an uproar in the criminal underworld. Many of the other side's soldiers are now in jail due to informing and they are furious. They go to war. Yay.
That's my best effort.