One interesting plot could be Naruto traveling to a dimension where the Akatsuki are the heroes. It would be a complete role - reversal, and Naruto would have to figure out how to interact with them. Another could be a dimension where everyone has a different type of chakra, like water - based chakra for all shinobi, and Naruto has to adapt his skills.
Well, in some 'naruto dimension travel fanfiction', there might be a plot where Naruto travels to a dimension where the Fourth Great Ninja War never happened. He could then see how different the ninja world is without that major conflict. Or perhaps he travels to a dimension where all the tailed beasts are free and live in harmony with humans, and he has to learn from that world how to better handle his own relationship with Kurama.
One idea could be that the main character accidentally activates a forbidden jutsu that transports them to different dimensions in the Naruto universe. For example, they might end up in a dimension where the Akatsuki has successfully captured all the tailed beasts and rule the world. They then have to find a way to team up with some of the remaining shinobi to reverse the situation.
One idea could be that Naruto travels to a dimension where all the female characters from different Naruto arcs are united. They all fall for his unique charm and his skills as a ninja. He has to balance his new relationships while also finding a way back to his own dimension.
A really exciting plot could involve Naruto getting trapped in a time - loop within the Juubi dimension. Every time he tries to find a way out, he ends up back at the starting point. He has to figure out how to break the loop by solving a mystery related to the Juubi's power. This would require him to interact with different versions of characters he knows, who may have different personalities and motives in this strange dimension.
One idea could be Naruto getting trapped in a dimension where chakra doesn't exist, and he has to learn new forms of power. Another could be a dimension where the Akatsuki are the heroes, and Naruto has to figure out how to co - exist or change that world. Or perhaps a dimension where all the dead characters are alive again, but in different roles, like Itachi as a rogue ninja fighting against Konoha.
One idea could be Naruto being transported to a dimension where chakra doesn't exist, but he discovers a new form of energy and has to learn to use it from scratch. This would force him to adapt his fighting style completely.
One idea could be Naruto traveling to a dimension where all the villains have become heroes. He has to adapt to this new world order and figure out how to get back to his own dimension.
One idea could be Naruto arriving in a dimension where chakra doesn't exist and he has to learn new powers. Another could be him meeting alternate versions of his friends in different dimensions, like a super - evil Sasuke in one dimension. Maybe he also discovers a dimension where the Akatsuki are the good guys and he has to figure out how to work with them.
One interesting plot idea could be Nightwing getting accidentally transported to a dimension where the laws of physics are completely different. He has to quickly adapt to survive and find a way back home. Maybe in this dimension, his acrobatic skills are useless at first, but he gradually figures out how to use the new environment to his advantage.
Well, in some Naruto fanfictions about dimension travel, Naruto might end up in a dimension where the tailed beasts are the dominant species. He then has to figure out how to communicate with them and maybe even form alliances. Or he could travel to a dimension where there is no chakra, and he has to learn new forms of power to survive and find his way back.
Another concept could be Naruto having to adapt to different power systems in the dimensions he travels to. Maybe in one dimension, physical strength is more important than chakra control, and he has to learn new fighting styles to survive.