Reducing reads in firestore

I am currently working on a project in which I face issue of reading millions of records in a day out of 17k total data . which seems to be quite enormous and the website isn’t hosted yet . I am bit confused about the working of algolia . Initially I thought the search results wouldn’t add reads in firestore becaise it’s indexing data in it own store but this has costed me alot of dollars . I will really appreciate if anyone can help me resolve this problem . Thanks