how is the TCP congestion control mechanism (TCP Reno, Vegas, etc) chosen? At the client/host level?

https://web.archive.org/web/20160103040648/http://www.isoc.org/inet2000/cdproceedings/2d/2d_2.htm

hello, just a CCNA here, so please pardon my ignorance :)

question: how is TCP congestion control chosen? according to the above page, it appears to be determined by the sender

if that's true, how is it determined by the sender? does it vary by application? Does my Chrome browser always use a certain kind of TCP congestion control?

is it possible for middle devices to modify the TCP congestion control method?