I have appeared in multiple companies for frontend interviews, but i always keep failing the System Design round. I have attended 3 system design rounds and all of them had completely different patterns and approaches. I watched jser videos on youtube and came up with a guideline to approach these interviews but none of that seems to work. Can someone help me with resources or tips so that i dont mess up my interviews further:

System design questions asked till now:

Company 1. Build a modal that allows users to specify amount and choose a type of crypto from the dropdown. (Type of crypto to be fetched from api)
Company 2. Build a grocery app that shows all the available items in a list, user should be able to view a product's details, add a product to favorites and view favorites.
Company 3. Build a plasma screen app that shows the number of users signing up to the website in real time.

I have around 2.5y of experience and most of the questions asked (eg: SEO or Polling) is something i have never implemented in my current company because i dont work on a customer facing app.

Any resource would be helpful.