Thank your everyone for your answers and such goodwill ! 
I hope it may help other Bitcoin newcomers !
TBH I already tried Green and mycelium but not satisfied
Electrum is not available on iOS 
I will take a good look at Bread wallet and bitcoin.org choose your wallet to help my choice.
To give more accuracy in this topic, this answer makes me realize that is exactly this kind of online wallet or service that I am looking for.
Meaning an online service that regroup its users’ transactions and results in a fee reduction or cancellation.
I hope it may help other Bitcoin newcomers !
TBH I already tried Green and mycelium but not satisfied
Electrum is not available on iOS I will take a good look at Bread wallet and bitcoin.org choose your wallet to help my choice.
your freebitco.in account takes a slightly smaller fee compared to a transaction's fee because they are paying a lot of users at once in one transaction which would decrease the size by a little bit so it decreases the total fee
To give more accuracy in this topic, this answer makes me realize that is exactly this kind of online wallet or service that I am looking for.
Meaning an online service that regroup its users’ transactions and results in a fee reduction or cancellation.