Google has so far always used flagship Qualcomm Snapdragon chipsets on its high-end Pixel devices. The Pixel 3a series and the upcoming Pixel 4a are an exception and make use of non-flagship mid-range Snapdragon chips which make sense since they are not flagship smartphones. For the Pixel 5 series, it is looking likely that Google intends on using Qualcomm's Snapdragon 765G chip instead of its current flagship chipset, the Snapdragon 865.
Code found inside a leaked Google Camera APK from the Pixel 4a has revealed two things about the Pixel 5 series: the lineup carries the codename 'bramble' and 'redfin' and that they will feature a telephoto camera. The inclusion of a telephoto sensor is not surprising since Google included it in the Pixel 4 series as well.
As for the 'bramble' and 'redfin' codenames, they have leaked before as well in AOSP. Google is developing these devices on Qualcomm's Snapdragon 765G mobile platform. This is the San Diego-based company's second-best chip for 2020. It is seemingly 20-40% slower than the Snapdragon 865, though it does pack 5G courtesy of an integrated X52 modem. The Snapdragon 765G is actually the successor to the Snapdragon 730 which Google will be using inside its upcoming Pixel 4a.
It will be a bit surprising if Google ends up launching the Pixel 5 series with a non-flagship Snapdragon chipset. However, the use of a premium mid-tier chip could allow the company to price the handset more reasonably instead of slapping a $1,000+ price tag on it that is becoming increasingly common nowadays for flagship phones.