what I'm trying to know about soft wallets like Bitpay, Enjin or BitCoin Core wallets , do they store bitcoins on the device or on internet ?
Your bitcoins are stored on the blockchain, which is publicly available to every bitcoin node. Anyone who knows your bitcoin address can see the balance of that address. But those bitcoins can only be spent by knowing your private key. So as long as you have your private key, you can spend your bitcoins from any device.