Apps unavailable due to region, keep subscriptions

To change your Apple Account country for the App Store you are required to cancel existing subscriptions and spend any balance on your account, and must wait for the canceled subscriptions to completely expire.

So, yes, you will lose your subscriptions once you cancel them.

click here ➜ Change your Apple Account country or region - Apple Support

The support article Change your Apple Account country or region - Apple Support describes how to change your country setting on everything using your Apple Account, and the requirements and results of doing this. You will have to meet all of those requirements, including canceling subscriptions and waiting for them to expire (or contacting Apple and asking Apple to end them immediately).

Apple's system is designed so that changing country on account is only feasible if you are truly taking up long-term residency in another country, not a one month visit. Even if you did not have to cancel your subscriptions, you might find things such as required payment methods still made this difficult for you to do.