Your description is kinda confusing.
If you want to use something as a tablet, why don't you get a tablet? If you want it to be small, then you need a phone, so I really don't know what to suggest here
Other than that, you have to give us a budget. There are thousands of options out there!
As for the s4 mini, that phone was 100% crap 5 years ago. I wouldn't recommend that to literally anyone today.

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