I always wanted to buy a 4*4 car because it’s safer and stronger. I
think it’s a manhood thing.
I mean that men usually like big and strong things as it’s part of their childish nature, and I’m not sure whether I used this expression correctly and I wonder whether it is normal and appropriate expression. I don’t want to find myself in a very embarrassing situation.
In your example sentence
I always wanted to buy a 4×4 car because it’s safer and stronger. I think it’s a manhood thing.
Manhood is not quite the expression to use, as @MichaelHarvey points out it could be interpreted to mean a specific part of a male’s anatomy.
The usual expression is:
It’s a guy thing.
Meaning it’s mainly associated with “guys” which is a more idomatic expression, you could also say
It’s a male thing
Which definitively draws the line based on gender. But using “guy” has other connotations: drinking beer, hunting, poker, chasing women which are generally things that “guys” do.