Manufacturers don’t make displays under 6 inches available for purchase, with special cases (such as the iPhone Mini) being made under exclusive contracts. The best lead they have so far is to try to use displays designed for the front part of a foldable phone, but they’re yet to strike an agreement.
TIL that display manufacturers are also part of the reason why we aren’t getting small phones and why it’s probably even harder for manufacturers like Fairphone to make them.
Sony used to sell smaller phones in general. Plus, they all come with headphone hacks.
Nothing quite as small as the Mini, but the Sony Xperia 5 V is relatively compact in a “thin but tall” way. Sadly, I don’t think they’re still producing their Compact lineup.
If you want to go tiny, there’s the Unihertz Jelly Star:
Unihertz sells a phone with a 4.2" screen, but it’s still tall because there’s a physical QWERTY keyboard underneath the screen.