The 2021 iPhone SE might continue sporting the same A13 Bionic SoC as the current iteration, according to information from known leaker Mauri QHD. This makes perfect sense as the A13 is a pretty powerful chip and gets barely pushed on the iPhone SE. The 2021 iPhone SE is also expected to sport an design similar to the iPhone 8, but that is not clear at the moment.
https://www.notebookcheck.net/Apple-may-continue-using-the-A13-Bionic-SoC-and-retain-the-iPhone-8-esque-design-in-the-2021-iPhone-SE.478474.0.html