Can I place a Cover order on the mobile app?

No — Rupeezy does not currently support Cover orders on the mobile app. (A Cover Order is an intraday order type that pairs an entry order with a compulsory stop-loss leg for reduced margin.)

If you want to attach a stop-loss to your position, use a GTT (Good Till Triggered) order instead. A GTT lets you set a Stop Loss trigger (and, with OCO, a Target as well) that stays active until it's hit. See How to place a GTT order on the Rupeezy app.