導購口語:

The shirt is one size smaller than that one.
這件襯衫比那件小一號。
Does this dress come in any other color or size? I think I need extra large size.
這件衣服有沒有別的顏色和尺寸？我想我需要加大號的。
I'm afraid it's a little bit big. Have you got any smaller size?
我覺得有點大，有小一點的嗎？

語句解析:

Extra large size 加大號的；come in any other color or size 有別的顏色或尺寸，這里的come in不是進來的意思，而是表示“存在上市”之意；a little bit big有點大，a little bit固定詞組，意思是“有點，有幾分”。

情景再現:

This seems to be a bit too narrow.
這個似乎太窄了一點兒。
It's a little large. It doesn't fit me.
大了點，穿著不太合身。
This one is slightly longer / shorter.
這個稍長/短了一點兒。