SEPA Instant payment is executed only if both the sender and receiver banks are connected to the SEPA Instant scheme.
At the moment, almost 3000 banks from 23 countries are part of the SEPA Instant scheme, and in the future, this list will expand to connect all banks in each of the 36 SEPA participating countries, thereby removing geographical borders for payments within Europe.
You can check if your bank supports SEPA Instant here: https://www.iban.com/
Copy your IBAN into the search bar. You will see if SEPA instant is supported under “SCT-INST”.