Is a wife obligated to obey her husband if he forces her to wear fashionable, attention-grabbing clothes, even if she wears the hijab?

The legal hijab does not have a specific form, but rather has conditions and specifications. If these are met in a garment, then it is lawful; if they are not, then it is not. It appears that what the husband is asking for involves adornment, which is not permissible except within the home, and on condition that no one sees you in it except women, your husband, or an unmarriageable mahram. This is because one of the conditions of the legal hijab is that it should not be an adornment in itself. Therefore, you are not permitted to obey him, and you should gently inform him that this is not permissible, and that the command of Allah takes precedence. You can also show him the fatwas that clarify the characteristics of the legal hijab.