Your Apple ID accounts takes it region from the initial account setting/billing address, and that should match the region of the payment method (i.e. where cards were issued).
As far as I know, you wouldn’t have to change region while in the EU, as far as Apple is concerned. But if you want to set a new country or region, then you will need a new local payment method, and old purchases may not be available while the account is set to that new region. The account region set the Store region as well. Items (films, music, ebooks) that are not available in the new region, will not be available after changing to the region. Items that happen to be available in both regions as the same item ID, may stay available, but will now offer different local language options (e.g. German instead of Dutch).
To keep your films from your Dutch purchases, you may download those, before changing the account region. As detailed in: Change your Apple ID country or region - Apple Support
Changing countries for your account will require canceling subscriptions and re-subscribing.
Changing countries for your account will require zero’ing any account balance.
Changing countries for your account will require a new local payment method.
Changing countries for your account will require dismantling any Family Sharing group, and setting it up again in the new country. All group members must have accounts for the same country or region.