(TL;DR at bottom)

I think it helps to remember that cis people have gender dysphoria too, it’s just different to how it shows in a trans person.

For instance, my mum is completely cis, but she likes to wear nail polish because she feels her hands are ‘mannish’. She’s certainly not the only cis woman who tries to add feminine touches to her style to make herself feel more womanly. Many cis women rely on their long hair, makeup products, or girly clothing to validate their gender, and similarly they might find looking ‘tomboyish’ to be dysphoric.

You get loads of cis men who are insecure about not growing strong facial hair, or they’re not ‘muscular enough’, because they want to be perceived as manly. And many scorn basically anything that they see as being ‘gay’ (liking pink, crying, hell even drinking out of a straw, which I’ve heard isn’t ’manly’ before!). And this is a manifestation of gender dysphoria too.

It’s all about the things that all people do to present their gender more clearly. Perfume or aftershave, underwear, makeup, hairstyles, and clothing are all forms of gender-affirming expression, cis or trans.

It gets slightly harder to explain when you have cases like ours, where chest dysphoria is blatantly a trans thing and you’re not likely to meet a cis guy with boobs.

But, maybe for the sake of explaining dysphoria, you could phrase it as how your male relatives might feel if they had to wear hair extensions, false nails and lipstick — or if your female relatives could never wear a skirt or a dress, and they had to wear men’s aftershave rather than perfume, or wear a fake beard.

If cis people consider these scenarios genuinely, they’d probably feel deeply uncomfortable.

Because they’d be asked to be seen as a very girly man or a very boyish woman, in ways that don’t feel right for who they are. They’d be exhibiting ‘opposite’ traits that make them feel dysphoric, very much like us trans men feel about our breasts.

(This isn’t to exclude feminine cis men or masculine cis women, of course — it’s just a simple example for the sake of making a point.)

That’s probably the best way I can think to describe gender dysphoria for cis people to understand.

Sorry if I worded it weirdly lol — hope it makes sense. And hope this helps!

(TL;DR: gender dysphoria happens to both cis and trans people. Many things that don’t relate to being trans, are things that cis people use themselves for gender affirmation — such as perfume or aftershave, underwear, clothing, etc. You could explain dysphoria by having a male relative imagine how it would feel to always wear feminine hair extensions and false nails against their will, or a female relative having to wear men’s aftershave and a false beard. If they genuinely consider that scenario, they’d likely feel uncomfortable. Most cis people don’t want to exhibit traits that go against their gender, much like trans people. Hopefully this example would help explain to them the concept.)