How to ignore case sensitive rows in PostgreSQL

Use Non deterministic collation (only PostgreSQL version >= 12):

From https://dba.stackexchange.com/questions/101294/how-to-create-postgres-db-with-case-insensitive-collation :

CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);

Edit

From https://stackoverflow.com/a/59101567/2928168 :

    CREATE COLLATION case_insensitive (
      provider = icu,
      locale = 'und-u-ks-level2',
      deterministic = false
    );

    CREATE TABLE names(
      first_name text,
      /* Example collation used in schema directly */
      last_name text COLLATE "case_insensitive",
    );

    insert into names values
      ('Anton','Egger'),
      ('Berta','egger'),
      ('Conrad','Egger');

    select * from names
      order by
        last_name,
        /* Example collation used only in some query */
        first_name collate case_insensitive;