Your question seems to imply generality ("systems design"), but the description of your question seems to imply specific tooling (e.g., Kafka).
Many people have mentioned really good books (e.g., DDIA). Such books are good for gathering a general knowledge about "systems design", but you will be still clueless about the differences between Kafka and Rabbitmq until you actually read their documentation manuals.
There is no shortcut I'm afraid. If you want to "understand seemingly endless options when it comes to data handling on backend side" you will have to read the corresponding seemingly endless documentation manuals. How else would you know about the advantages or disadvantages of, let's say, InfluxDB over Postgres if you don't read their manuals?
Many people have mentioned really good books (e.g., DDIA). Such books are good for gathering a general knowledge about "systems design", but you will be still clueless about the differences between Kafka and Rabbitmq until you actually read their documentation manuals.
There is no shortcut I'm afraid. If you want to "understand seemingly endless options when it comes to data handling on backend side" you will have to read the corresponding seemingly endless documentation manuals. How else would you know about the advantages or disadvantages of, let's say, InfluxDB over Postgres if you don't read their manuals?