We are now seeing some affordable Pixel lineup since Pixel 3, for this year we are waiting for Pixel 5a. For the same, some images surface on the internet. The design looks quite familiar to Pixel 4a. Both of these smartphones are quite similar. The dimensional size of Pixel 5a (as per leak) sits between that of Pixel 4a and Pixel 4a 5G.
The unibody design from Google will be plastic built as we have seen in Pixel 4a. The screen is a 6.2" FHD+ OLED with thin bezels and forehead but a more significant chin. The position of the front-facing camera is the same as that of Pixel 4a, on the left top corner.
Rear camera placement is similar to Pixel 4a. The fingerprint scanner is given on the back and a 3.5mm headphone jack is still present, bundled with a stereo speaker setup.
You can clearly see most of the features and dimensions looks similar to Pixel 4a, so in design, there won't be any difference between Pixel 4a and Pixel 5a, the only difference that may present is in the hardware part especially, SoC.