In the admin panel of the store, you can find the default country setting.
To do this, go to Settings → General Settings → Info about store and scroll down to the Country field.
For most sites, your country is selected here by default.
If you plan to carry out your main activity in another country, for example, in Poland, select the value you need from the drop-down list in this field.
When placing an order, customers will see the drop-down City list for the country selected in this field.
You will also be able to select the default country's cities in the settings of delivery options that are tied to a specific city.
If your store sells to different countries, set up the country selection field at checkout. Read more about this in the instructions here: