Streaming · Plain-English answer
Not on its own. Apple and Google tie your store region to your account's billing country and payment method, not just your IP address, so connecting to a VPN abroad will not switch catalogues by itself. Changing region properly means updating your account country, which affects payments, subscriptions and purchases.
Streaming sites decide your region per visit from your IP address, which is why VPNs affect them. App stores work differently. Your Apple ID or Google account carries a country setting anchored to your billing address and payment card, and the store serves that country's catalogue wherever you happen to connect from.
A VPN can change what the storefront looks like before you sign in, and Google Play checks IP address during the one official region change it allows per year, but neither store lets a signed in account simply drift between countries by IP.
On Apple devices you change country in your Apple ID settings, which requires a payment method and billing address in the new country and no active subscriptions or store credit. Google Play allows one region switch per year with a matching payment profile, and you lose access to credit from the old country.
The honest summary: a VPN is useful alongside an official region change, not instead of one. It changes where your connection appears to be, while the store cares about where your account is registered.
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