You have a full example here http://docwiki.embarcadero.com/RADStudio/Rio/en/Executing_SQL_Scripts_%28FireDAC%29
For example, the following Firebird script creates a database, and can be executed using TFDScript:
SET SQL DIALECT 3;
SET NAMES UTF8;
SET CLIENTLIB 'C:\fb25\bin\fbclient.dll';
CREATE DATABASE 'E:\Test2.ib'
USER 'sysdba' PASSWORD 'masterkey'
PAGE_SIZE 16384
DEFAULT CHARACTER SET NONE;
SET TERM ^ ;
CREATE PROCEDURE MY_PROC RETURNS (aParam INTEGER) AS
BEGIN
aParam = 10;
END^
You should use CreateDatabase=Yes connection definition parameter additionally to other required parameters: http://docwiki.embarcadero.com/RADStudio/Rio/en/Connect_to_Firebird_(FireDAC)