How to sign an encoded approval call?

[Madeindreams]

when we Encode a function call to be passed has low level call. The call get executed in the context of the contract.

How could I, for example;
Sign an approval to be made in a low-level call on behalf of the msg.sender.

For instance

         iface = new ethers.utils.Interface(JSON.stringify(APPROVE_ABI));
         sig = "approve(address, uint256)";
         let data = iface.encodeFunctionData(sig,[address,uint])

Is there a way to sign this so the contract make the approval call on our behalf within the actual call that leads to the transfer?

Is it even possible to do??

In solidity by example they have this example base on 2 contracts. Can it work with EOA?

  function setVars(address _contract, uint _num) public payable {
        // A's storage is set, B is not modified.
        (bool success, bytes memory data) = _contract.delegatecall(
            abi.encodeWithSignature("setVars(uint256)", _num)
        );
    }

If I turn this call into an approval. The call is working but the allowance is not on my account it remains on the contract account.

What is the mechanic that the Permit feature use then?? Does it have to be implemented in the token contract??

Indeed The approval can't be passed like that. The ERC20 Permit also needs to be part of the token contract.