code from the KeyManager contract from LUKSO to explain omitting parentheses in if statements

LSP6KeyManagerCore.sol

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.6;

// imports and errors declarations omitted for brievity ...

/**
 * @title Core implementation of a contract acting as a controller of an ERC725 Account, using permissions stored in the ERC725Y storage
 * @author Fabian Vogelsteller, Jean Cavallera
 * @dev all the permissions can be set on the ERC725 Account using `setData(...)` with the keys constants below
 */
abstract contract LSP6KeyManagerCore is ILSP6KeyManager, ERC165 {
    // libraries and other functions omitted for brievity ...

    /**
     * @dev verify the permissions of the _from address that want to interact with the `account`
     * @param _from the address making the request
     * @param _data the payload that will be run on `account`
     */
    function _verifyPermissions(address _from, bytes calldata _data)
        internal
        view
    {
        bytes4 erc725Function = bytes4(_data[:4]);

        // get the permissions of the caller
        bytes32 permissions = ERC725Y(account).getPermissionsFor(_from);

        // skip permissions check if caller has all permissions (except SIGN as not required)
        // ...

        if (erc725Function == setDataMultipleSelector) {
            _verifyCanSetData(_from, permissions, _data);
        } else if (erc725Function == IERC725X.execute.selector) {
            _verifyCanExecute(_from, permissions, _data);

            // more permissions checks to verify if the address making is allowed to:
            //    - interact with a specific address
            //    - run a specific function on the contract being called
            //    - can interact with a contract implementing a specific standard interface
            // (omitted for brievity)
            
        } else if (erc725Function == OwnableUnset.transferOwnership.selector) {
            if (!permissions.includesPermissions(_PERMISSION_CHANGEOWNER))
                revert NotAuthorised(_from, "TRANSFEROWNERSHIP");
        } else {
            revert("_verifyPermissions: unknown ERC725 selector");
        }
    }

    // other functions omitted for brievity ...
}