(With all due my respect, pardon my weak grammar please, I am no native English commander.)
I have no idea why but wearing guys' clothes has been killing me, especially fast fashion brands like Adidas, Abecrombie, Hollister, Uniqlo, alike. No shops sell short-short pants for guys, because people think exposed "limb", tseticles and hideous leg muscles and hairs are hideous, right? Every dudes' clothes in these days makes wearer much more manly and that devastates me. Thus very cute, girly, and juvenile clothes such as AUTHENTIC FEMALE kimonos(yukatas), cute panties like shimapan(Japanese striped cute panties), obsolete Japanese school swimsuits(skoomizu) or at least very short pleated skirts or dresses full of frills and ribbons have come to my attention. Yes, they can be seen in doujins or animes, but I gave up watching mangas or animes long ago. Most of them are full of phobia and obsolete fixed gender roles. The only reason to still browse pixiv (doujin site) is learn about those juvenile fashions....

Yeah, so I have been googling and googling to find them. But reality sucks.
Since there are very handful of colossal women in Japan

Proportion of colossal women in Japan
180cm 17-year-old gal … 0.1 ‰
181cm 17-year-old gal … 0.1 ‰
182cm 17-year-old-gal … 0.1 ‰
183cm 17-year-old-gal … 0.1 ‰

Practically no online shops sell larger than 5L sized Kimonos or yukatas can cover women taller than 6ft.
There might be some larger ones but they are just baits attract tourists who are unaware of real kimonos.
Likewise, general big-sized female clothes are too mundane, plain and characterless, whether they are Japanese clothes or western clothes.
In here Korea, 90% of female clothes are brown, grey(pigeon color, rat color), black.....I will kill myself if I should look like mice.

As for underwear, online Japanese souvenir shops sell shimapans for men but I am unsure if they are functioning as real underwear.

Many people just say go find some tailors.....where? where can I find less bigot tailors?
I do not know how Japanese people think, they always hide something.....
They act very kindly in front of me but who knows if they scorn me while they sew something for me?

Finding tailors or reverse-engineering clothes and sew mine-Are they only solutions?