Yes. You're unlikely to get a full ap-lux build, and lategame lux doesn't deal as much damage anyways. Build like a standard support, with an emphasis on ap. Your job is to shield and kite enemies from your adc. She's very good at it, too.
Idealism is seeing potential. Pragmatism is seeing consequences.
Supports build whatever their ADC/team needs. No matter which support you are, you should be building the same items. Locket if you need a shield, Aegis to make your team tanky, Shurelya's if you Gotta Go Fast(tm), Crucible if your team needs healing, Zeke's if you have 3 AD champs. Lux doesn't make a good support because by building these items you can't deal enough damage, and if you don't your utility isn't enough to play as a support viably.