Sony Xperia Z3 Compact is 4.6", but super brittle. The Huawei P10 is 5.1" and has a case that makes it a tank. The SOYES XS12 Cell Phone is 3.0", if you need smaller. Have you searched using GSMArena's phone finder?
The Sony Xperia Z3 Compact is from 2014 and tops out at android 6. The Huawei Huawei P10 Lite is from 2017 and tops out at android 8 (9 for the non-Lite). I hadn't heard of the SOYES XS11, but it looks like it does not support 4g (and 3g support is being shut down by various operators), and tops out at android 6.
So for current small android phones I'm guessing the unihertz Jelly 2 is one of the few remaining.
https://www.gsmarena.com/
https://www.gsmarena.com/results.php3?nHeightMax=135&nDispla...