Can an existing employee switch to non-local currency salary payments?

Yes, it is possible for an employee who has already been onboarded to switch to non-local salary payments as longer as they are a resident of a country where this is supported.
See also: In what countries is non-local currency salary payments offered?
To start the process, the Customer will need to submit a contract amendment request on Remote. Once the contract amendment process is complete, the employee will begin receiving their salary in a non-local currency.

See also: How to request changes to an employee's contract