Create a gin gin_trgm_ops index, using a sequelize migration. Once created you can use this sql command to verify the index was created properly: `SELECT * FROM pg_indexes WHERE tablename = 'table_name';`

migration.js

'use strict';

module.exports = {
  up: (queryInterface, Sequelize) => {
    return queryInterface.addIndex('Parties', {
      fields: [Sequelize.literal('name gin_trgm_ops')],  // <-- name = field name, gin_trgm_ops comes after the field name
      using: 'gin',
      indexName: 'party_name_gin_trgm_idx', // specify the index name manually otherwise sequelize will create party_
      unique: false,
    })
  },

  down: (queryInterface, Sequelize) => {
    return queryInterface.removeIndex('Parties', 'party_name_gin_trgm_idx');
  }
};

Verifying the index was created as expected: