Can Experiments be run for an offering that is not the default offering?

In my app I don’t use the current offering.

if let firstPaywallOffer = offers["first_paywall_standart_offer"]{
                    self.firstPaywallPackages=firstPaywallOffer.availablePackages.map({$0.storeProduct})
                }

I am getting my paywall offering like this. In the documentation experiment’s just change the current offering. How can I use experiments feature in my app. Do I have to use the current offering? 

 if let coinOfferings = offers["first_coin_offerings"]{
                    self.coinPackages = coinOfferings.availablePackages.map({$0.storeProduct})
                }
                if let specialOfferOfferings = offers["special_offer_offering"]{
                    self.specialOfferPackages = specialOfferOfferings.availablePackages.map({$0.storeProduct})
                }

The reason I use hardcoded id is that there are 3 different paywalls in my application and one of them is non-subscription packages.