Older version of Chrome are not publicly available but you can find and download the matching Chromium binaries from the Chromium build server.
To do so follow the procedure below (derived from Chromium wiki):
1/ Find the Full Version Number
You can lookup the full version number matching a release by searching in the Chrome Releases Blog
Example:
- Searching for “Chrome 69”
- We find this Blog Entry
- That lists the full version number 69.0.3497.81
2/ Find the Branch Base Position
Use the “Version Information” tool to find a Branch Base Position for the Full Version number.
To do that enter the Full Version Number and press lookup.
If the version returns an empty Branch Base Position try increment the last component of the version until you get a Branch Base Version.
Example:
Looking up 69.0.3497.81
retrieves no Branch Base Position
But looking up 69.0.3497.82
retrieves Branch Base Position: 576753
3/ Download the content for Branch Base Position and platform
Then download the content from the url where you replaced your platform and Branch Base Position value.
https://commondatastorage.googleapis.com/chromium-browser-snapshots/index.html?prefix=[platform]/[Branch Base Position]/
Where [platform] is either “Win_x64”, “Linux_x64” or “Mac”
Example:
for Chrome 69 on Linux
https://commondatastorage.googleapis.com/chromium-browser-snapshots/index.html?prefix=Linux_x64/576753/