Best way to build a Social Media Platform

[Jaguar2k]

Hello Everyone,
I am a fullstack dev and wanted to build a social media platform to explore the possibilities with different databases
But I am really struggling to decide what should be the best database or databases to implement all these features like:

• Community detection
• Trend detection (last year, month, week, day, 7hours, 15mn)
  — trending categories
  — trending posts
• Counters
  — total users
  — total friends
  — total posts and total per user
  — total comments etc…
• Search engine
  — search users / posts / categories (with trending ones at the top)

I understand that Graphdb are perfect for community detection but not for trend detections where time series db seems more adequate.
For the search feature I am not sure what to use to be able to search any keywords like name, lastname, posts, categories or even the content of a post.

The idea is to design it and test for 10 million users posting 10 posts a day each (at least )

Will you use only 1 database to achieve all that or will you use different databases and connect them together to get the best from all ?

Could you guys tell me what you will use to cover each of these feature please ???

Thank you for the time you’ve spend reading and helping me out

[Jaguar2k]

upping my message in case of others may be interested !