install httpfs;  -- once
load httpfs;

CREATE SECRET http (
    TYPE HTTP,
    EXTRA_HTTP_HEADERS MAP {
        'Authorization': 'Basic cG9zdG1hbjpwYXNzd29yZA=='
    }
);

.print Using read_text():
FROM read_text('https://postman-echo.com/basic-auth');

.print Using read_json_auto():
FROM read_json_auto('https://postman-echo.com/basic-auth');