For protractor side check out this page
Per its content, having this in your conf.js:
module.exports = {
  params: {
    login: {
      email: 'default',
      password: 'default'
    }
  },
    //  * other config options *
}
you can pass any parameter to it in CMD as follows:
protractor --baseUrl='http://some.server.com' conf.js --parameters.login.email=example@gmail.com 
--parameters.login.password=foobar
so you end up having this in your specs:
describe('describe some test', function() {
  it('describe some step', function() {
    browser.get(browser.baseUrl);
    $('.email').sendKeys(browser.params.login.email);
    $('.password').sendKeys(browser.params.login.password);
  });
});
For Jenkins just construct the command as follows:
protractor --baseUrl=${url} conf.js --parameters.login.email=${email}
--parameters.login.password=${password}
Another way if you want to just pass one parameter is have object in your config.js with mapping of all related params like this:
let param_mapping = {
    prod: {
        url: "https://prod.app.com",
        email: "prod@gmail.com",
        password: "Test1234"
    },
    dev: {
        url: "https://dev.app.com",
        email: "dev@gmail.com",
        password: "Test1234"
    },
    stage: {
        url: "https://stage.app.com",
        email: "stage@gmail.com",
        password: "Test1234"
    }
};
let parameters = param_mapping[process.ENV.CUSTOM_ENV];
exports.config = {
    baseUrl: parameters.url,
    params: parameters,
    // ...
};
and then start your process with an environment variable:
CUSTOM_ENV=dev protractor protractor.conf.js
Please note, I haven't tested this particular code now, but I did test the logic a little while ago, so this can be your approach