Yes. Fanfiction.net is also a good place to look. Some male OC fanfics might explore the idea of a male character who is friends with the main gang. For example, he could be an outcast like them but has his own unique take on the strange happenings in Hawkins. He might be into science or something and his knowledge helps the group in a different way compared to Dustin or Eleven.
One common theme is the male OC being a hero. He often steps in to help the main characters solve the mysteries of the Upside Down. For example, he might have some combat skills or be really smart with technology.
A plot could involve the male OC being related to one of the scientists who worked at the lab. He comes to Hawkins to find out what really happened to his relative. Along the way, he teams up with the kids and they uncover a conspiracy that goes deeper than they thought. Or perhaps the male OC is an artist and he starts having visions of the Upside Down through his art, which leads him on a journey to figure out what they mean.
First, think about his backstory. For example, where he's from in Hawkins or if he has a connection to the Upside Down. Then, consider his personality traits. Is he brave like Steve or more of a thinker like Dustin? Also, his relationships are important. He could be a new friend to the main group or have a rivalry with one of the existing characters.
One great 'Stranger Things 4 Fanfic' is 'The Upside - Down Revisited'. It delves deeper into the Upside Down and how the characters interact with the new threats there. It has really good character development, especially for Eleven. Another one is 'Hawkins' New Horrors' which focuses on the town's reaction to the events of season 4 and how the community bands together or falls apart. There's also 'Beyond the Gate', which explores what might be on the other side of the gates that keep opening up in Hawkins.
There's also 'Byers Brothers' Adventure'. This fanfic follows Will and Jonathan Byers on a side adventure that wasn't shown in the show. It has great character development and a really engaging plot.
You could have an OC that is a transfer student from a different town where strange things have also been happening. This OC could have some knowledge about the otherworldly events that the kids in Hawkins haven't encountered yet. Or make an OC who is a scientist's assistant, secretly helping the main characters by providing inside information from the lab. They might also be in danger because of this connection to the scientific side of the mystery.
I would recommend 'Hawkins' Hidden Love'. This fanfic delves deep into the lives of the Stranger Things characters in a gay context. The author does a wonderful job of creating a believable story line. It has a great balance between the mystery and drama elements that are so characteristic of Stranger Things, and the exploration of the gay relationships among the characters. It's definitely worth checking out.
In Stranger Things crossover fanfics, Dustin is quite popular. His intelligence and his love for science can lead to interesting interactions in crossovers, for example, in a crossover with a scientific - based fictional world. Max Mayfield is also a favorite. Her skateboarding skills and feisty personality can add a lot to crossovers. And then there's Will Byers. His connection to the Upside Down can be explored in many different crossovers, such as in a crossover with a horror - themed universe.
A Stranger Things crossover fanfic with the Avengers would be really exciting. The Hawkins kids could team up with the Avengers to fight off the Demogorgon which has somehow become a threat to the entire world. Or a crossover with Doctor Who. The Doctor could land in Hawkins and help the gang deal with the Upside Down, bringing his unique time - traveling and alien - fighting skills. Also, a crossover with the Ghostbusters would be fun. They could come to Hawkins to deal with the strange entities from the Upside Down using their proton packs.