Informal portraits are what you need if you want photos to post to your matrimonial profile, Instagram or dating profiles or any social media profile or feeds where 'informal' is the key word.
Informal portraits give you almost unlimited freedom to wear what you want, go for the look you like with informal portraits. There are not rules here (well within limits), whatever exist are defined by you and you alone. On the Portrait Sobriety Scale they are more informal than corporate or business portraits but not as experimental as fashion portraits. But then it is up to you.