Hi @jai welcome! It doesn't appear there's a way to filter by blog tags with our endpoints. When I make a get request with topic_id, it doesn't appear to have any bearing on the actual response returned. From the docs we have:
order_by
Return the posts ordered by a particular field value. Blog posts can currently only be sorted by publish_date. Use a negative value to sort in descending order (e.g. order_by=-publish_date).
The other parameters documented will work, but it doesn't appear blog tags do.