Populate database in bootstrap.js

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1
System Information
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I am trying to populate the database with a JSON file and following this tutorial: Import data from file | Strapi
It explains how you can add relational data without an example. I have categories in a separate collection, but struggling to source it as find is undefined.
Has anyone got an example I and others could use?
Or, tell me where I am going wrong?

const { offers } = require('../../data/offers.json');

module.exports = async() => {

  offers.forEach(offer => {

        const findCategoryItem = async (identifier) => {
            const result = await strapi
              .query["offer-category"]
              .find({ id: identifier });
            return result;
          };

        
         const offerCategory = findCategoryItem('604fa6eaa818b7e08079ee1a')

         console.log(findCategoryItem('604fa6eaa818b7e08079ee1a'))

          strapi.services.offer.create({
               offer_category: {Category: offerCategory.name}
           })

  })

}

Thanks