The USA falling into a shittier state is pretty much guaranteed to leave the rest of the world in a worse state, yes.
The problem is that this never happens as a consequence of the United States being in trouble, but is simply a totally disconnected development and often without any connection to the real situation on the ground.
The kind of things we can usually see are ideas like "oh, by the way, Germany has reestablished the Third Reich and they are invading Poland again"
"After the United States withdrew its troops from Japan, they have reestablished the Japanese Empire, annexed Korea, and they are genociding the Filipinos. Oh, if the United States had kept its troops deployed, in order to kept the Japanese in check, none of this would have happened"
"By the way, there are Russian tanks rolling through Athens, because since NATO collapsed after the withdrawal of United States, that means Russia can run unchecked through Europe," etc.
"Of course, since the United States was not there to PAY FOR EUROPE'S DEFENSE, so that they could afford to WASTE THEIR MONEY ON SOCIAL PROGRAMS, Europe's economy has imploded."
"Russia, Germany and Japan should have imploded too, specially now that they are fighting wars of expansionist aggression, but don't let reality get in the way of my jingiostic fantasy about how the world is a mess without a strong American military presence abroad."