That's two tags. What if I want to see canon hetero shit?
If you put two tags on the same line in your blacklist, it will only hide posts that have both tags. Posts with only one of the tags will still show up.
That said, I don't think out of character would be very useful for this. There are many instances of this that do not have the tag. I'm not even sure if it's a proper use for the tag since it might fall under artistic license (from the wiki). You might have better luck adding a specific character or franchise to the line instead.
That's two tags. What if I want to see canon hetero shit?
In Pixiv at least, the consensus seems to be no need to use heterosexual tag on couple who are canonically that. So it’s mainly for people looking for yuri/bl characters being hetero, or people blacklisting that kind of thing.