crossdreamers answered
Masculine in a feminine way
This is a tricky question, given that so many people think masculinity and femininity exclude each other. You are either masculine or feminine.
This view of gender expression obviously requires that masculinity is based on a list of traits, looks, behaviors, roles, abilities and interests that is exclusive to men, ditto for women.
Gender variance through history
This has never been the case in real life, in any culture, for the simple reason that men and women share all these traits, to a smaller or larger degree.
In this age of increased gender equality, we see that this is the case. If women are allowed to take over “male occupations”, they will, and if men are given the chance to take care of kids, they most often will.
“Looking masculine” is a relative phenomenon too. Lois XIV, king of France was considered “masculine” at the time he lived. Not so much in this day and age.
So the terms “masculine” and “feminine” cannot be clearly defined. We may know what we mean when we use the terms, but they are nevertheless fuzzy and ambiguous.
It is this that causes gender fundamentalists so much anxiety: The ambiguity threatens the clear gender binary they need to feel safe in their own life as a man or a woman.
I any age looking masculine in a feminine way is therefore relative to the current fashions and taboos. Where the boys of the 1980’s metal band Poison “masculine in a feminine way”? I guess they were at the time.
But this way of dressing up would not be considered masculine today.
Gender is increasingly expressed through fashion, not through social roles
Precisely because there is more gender equality, men have had to find other ways of safe guarding their masculinity than being the family provider.
Your occupation or social role no longer defines your “manhood”, so men often make use of fashion and performance to signal their “manliness.” I think the bearded, rugged, hipster father is a clear sing of this. He might be pushing the baby stroller, but he is still seen as the man.
What would pass for a “masculine femininity” will also vary from local culture to local culture. To use an American example: The dress code will probably be much more open and diverse in a big liberal city like San Fransisco than in a small conservative community in the rural Midwest.
So it all depends on where your friend lives.
Finding inspiration in Asia
In North America and Western Europe it was easier to mix masculine and feminine clothing and expressions in the 1980’s than it is today. I would therefore suggest that your friend takes inspiration from the gender variance found in many Asian cultures today, including South Korea, China, Thailand and Japan.
You find this in movies, anime, manga and pop music.
It seems to me that few question the gender of male K-pop stars, for instance (unless the ones questioning are far right homophobes and transphobes). Yet, these young men are allowed to add feminine clothes, colors, hair styles and accessories to their masculine presentation.
Given that K-pop has become so popular outside Asia, I would think that this masculinity with feminine expressions would be understood in Europe and the Americas too.
You say nothing about your friends gender identity. Do they see themselves as a cis man, a nonbinary person, transfeminine maybe or even trans? All of this will obviously color the way they want to express themselves.
I have interpreted your question to mean that your friend is assigned male at birth. But even if they are presenting as female, they can take inspiration from Asian pop and movie stars.
What really matters here is what makes them feel good about themselves, i.e. the kind of expression that most clearly express who they truly are.
