I need to get older versions of Chrome - not chromium - for Mac OS X specifically, 86 & 83 and all the guides online are for windows users. I'm fine to download from third-party sites but only a couple of blatant scams pop up for google searches.
21 Answer
If you only need the User Agent to be sent in a specific format, you can change it in Safari, to whatever you want it to be, from the Develop menu.
Open Safari Prefs > Advanced to enable the Develop menu
Then Develop > User Agent > Other… & you can type any agent string you like
First string is real, second is 'fake'. (I didn't check version/build for accuracy)