How to create IPA file from visual studio for Xamarin Forms project

Long story short, to build an .ipa, choose AppStore (or Ad-Hoc, Release) | iPhone as solution configuration and build the project. After build, you'll find the .ipa file in project's output directory (for example, bin\AppStore). Of course, you have to have corresponding provisioning profiles configured in Xcode but this is another question. More here.

Is it possible to release app from Windows machine only or I need to use Mac physically

You need an active connection to macOS to build your .ipa from Windows. And you need to upload the first build from macOS with Application Loader. Uploading can be done either physically from macOS or remotely but not within Visual Studio.

If I need to use Mac then for which steps while releasing app to App Store

The same as above. You need macOS connection for compilation (building .ipa) and for uploading your first build (.ipa) to App Store Connect. Subsequent uploads could be done without macOS.

We are releasing app to App Store using Application Loader or Xcode, Can we do it from Windows machine.

Publishing a release can also be done using services like App Center. However, the first build should be submitted by Application Loader from macOS.

Can we access Xcode from VS in order to release app to App Store

No. Visual Studio uses Xcode for building process. Publishing to App Store Connect directly from Visual Studio is not possible for now.

If I want to connect real device(to visual studio as targeted device) to create IPA file do I need to connect it in Mac or PC(Via USB cable) in order to get in VS PC

You need to connect your device to Mac. However, to build an .ipa, you don't need any iOS device connected.

To create IPA file do we need Mac machine connection

Again, yes, you do. Compiling, building, and making an .ipa file are the same things in this context.

Is it possible to release app from Windows machine only or I need to use Mac physically

You will need Application Loader which ships with XCode to submit your IPA to Apple but you can generate the release IPA directly on windows too.

If I need to use Mac then for which steps We are releasing app to App Store using Application Loader or Xcode, Can we do it from Windows machine. Can we access Xcode from VS in order to release app If I want to connect real device to create IPA file do I need to connect it in Mac in order to get in VS PC

Visual Studio 2017 does not currently support the Archive for Publishing workflow found in Visual Studio for Mac. But you can still generate the IPA and then send it to Apple from a Mac machine later on.

Check the docs: https://docs.microsoft.com/en-us/xamarin/ios/deploy-test/app-distribution/app-store-distribution/publishing-to-the-app-store?tabs=windows

Here is a blog on (How to create *.ipa file in Xamarin Forms) :

https://xamarindevelopervietnam.wordpress.com/2016/05/12/how-to-create-ipa-file-in-xamarin-forms/

However I would also prefer you to look into CD CI. Continuous Development and Continuous Integration system. This will help you not only to build the .apk and .ipa for your xamarin projects but also provides you the efficient way of build distribution.

There are several tools available based on your version control. Please check these links :

https://devblogs.microsoft.com/xamarin/continuous-integration-for-ios-apps-with-visual-studio-team-services/

https://docs.microsoft.com/en-us/xamarin/tools/ci/intro-to-ci

There is a video illustration of doing this in visual studio :

https://www.youtube.com/watch?v=P9cOCEuuEOE