Trained on PonyDiffusionV6. Contains 11 outfits from Persona 5 Royal, both from the story and some of her DLC outfits:
Default appearance: defSumi, long hair, ponytail, red bow, school uniform, black blazer, white turtleneck, bowtie, plaid skirt, pleated skirt, black pantyhose, red shoes
Phantom Thief, Violet: ptSumi, long hair, ponytail, black hair ribbon, black choker, black jacket, open jacket, black leotard, cleavage, silver belt, silver rose, frilled sleeves, red gloves, black thigh boots
Add "mask" to equip her Phantom Thief mask, it can be a bit janky though.
Casual outfit: casSumi, long hair, ponytail, red hair bow, polka dot shirt, off shoulder, white shorts, sandals
Try "aqua polka dot shirt" if it's showing up red. May need to add "short sleeves" as well.
Summer uniform: sumSumi, long hair, ponytail, red hair bow, yellow cardigan, long sleeves, collared shirt, plaid skirt, white socks, brown loafers
January winter outfit: janSumi, long hair, ponytail, red hair bow, winter clothes, black coat, red scarf, long sleeves, mittens, open coat, plaid skirt, black pantyhose, red loafers
Winter casual: winSumi, long hair, ponytail, plaid hair bow, red winter jacket, buttons, black turtleneck, black pantyhose, black shoes
Gymnastics outfit: leoSumi, short hair, single hair bun, blue leotard, blue choker, long sleeves, short dress, flats
Dance outfit (DLC): dncSumi, long hair, ponytail, red hair ribbon, heart earrings, red polka dot crop top, collared shirt, puffy short sleeves, tied shirt, midriff, plaid skirt, bracelet, red thighhighs
Swimsuit (DLC): swimSumi, long hair, ponytail, striped hair bow, pink frilled bikini, off shoulder, bikini skirt, flip-flops
Christmas outfit (DLC): xmasSumi, long hair, ponytail, fur hat, snowflake earrings, fur-trimmed dress, fur-trimmed gloves, fairy wings, snowflake print pantyhose, fur-trimmed boots
Fashion outfit: wildSumi, long hair, hair down, sunglasses, leopard print, print scarf, print shirt, clothes writing, layered sleeves, striped sleeves, fingerless gloves, yellow leggings, green socks, pink sandals
Colors on this outfit may be very inconsistent.
Custom outfits: rndSumi, long hair, ponytail, red hair bow
May need to add "red hair, red eyes" for consistency.
You can also swap out "ponytail" and whatever bow/ribbon the outfit normally has for "hair down, glasses" for her alternate look. Might not work as well on some outfits and will probably require adding "red hair" more often. Try some things out.