Stop in next week for more spellcasting tips from Advice Goblin.
You can seem 1 foot shorter or taller and can appear heavier or lighter. You must adopt a form that has the same basic arrangement of limbs as you have. Otherwise, the extent of the illusion is up to you.
Every RPG group I have ever been with has used either a magic item or spell to make change purely for cosmetic reasons. This is true regardless of gender and how power gaming the group is. The Cloak of Billowing is a 5e item favorite and is usually requested at item creation or in the first magic shop. I do want to get Mask of Many Faces just for fancy dress on my next character now.
Personally, I'm a big fan of the 'useless magic item' and try to get one to each of my players. Lots of them are cosmetic: helmets with glowing eyes, cloak of billowing, squeaky shoes.
Sometimes they're just weird, like the wand of create wand which is a one-charge wand that crumbles to dust after being used to make a wand of create wand
I have a (very) long running 3.5e game with a group of friends that is about to wrap up before the end of this year. Every character is level 19 and we got here the hard way, using XP count from stat blocks. Suffice to say we've made a lot of money and optimized our builds to a considerable degree.
On my character sheet right now, inside of my Big Ass Bag Of Holding™️, I'm just going to copy and paste this directly (gold count is the cost of the item in case I ever want to sell these - don't worry, I won't) :
Full Pimp Suit Ensemble :
25000gp, Rod of Splendor (gives charisma bonus +4 and an extremely swanky suit)
1000gp, Embroidered silk and velvet mantle with moonstones
9000gp, Gold cup set with emeralds
inside of
2500gp, Mythril bound mahogany treasure chest
I've only had one opportunity to actually use this so far, but it was brilliant, and I plan to pull it out again after we wrap up this campaign and I take over the late lich king's kingdom on the moon. I think it'll look nice for my coronation.
Yeah, it's ambiguous. I interpret the "you can be one foot taller or shorter" to mean you, and something like a hat or ridiculous hair can just be as large as you like so long as it still looks like an item of clothing and not (say) a billboard.
Of course, at very large sizes, something's going to clip into the illusion every now and then, so it'll obviously be an illusion to anyone who is around it for more than a few minutes. I'm imagining small birds trying to land on it and faceplanting into your head.