How to deploy case-insensitive embedded firebird database?
The syntax you're looking for is here


  CREATE {DATABASE | SCHEMA}    ...    [PAGE_SIZE [=] size]    ...
  [DEFAULT CHARACTER SET charset [COLLATION collation]]    ...
  [DIFFERENCE FILE 'filepath']
  
  size  ::=  4096 | 8192 | 16384


Also check out this page and this link from it specifically
about case insensitive searches and collations on columns.

The good news is that you can set it both by database and column.

Also, check this out - you can also use "shadow" columns if you
can't get exactly what you want "out of the box" - i.e. UPPER()
function.