Before you can start creating a template, be sure to add all of your services to the list of items. It takes a few simple steps, check out how it's done here. https://help.bloom.io/en/article/adding-invoice-items-2rpcmw/
Once you've got those added, head over to the Invoice Templates tab and open up New Template. Here is where you can build a specific invoice that would be available to send out every time the same type of service/session is booked.
Fill out the text fields in regards to the package you offer. You'll find all of your items in the drop-down menu under the Item Name field. You can add as many as needed by selecting the Add another item button.
Just like creating an invoice inside your projects, add any additional details to the invoice such as a discount, whether you'd like to add a retainer or any specific payment instructions you may have.
Hit Save and you're done! Your new invoice templates will be available when creating/editing a project or booking with your client under the Saved Templates button at the top of the invoice.