Across 3,519 ranked games on patch 16.21 in Master and above, Jhin mains win 52.3% of their games in the bot lane.
Their most common build appears in 24.7% of those games and wins 51.4% of its 868 games.
It starts 
Health Potion and 
Doran's Helm, completes 
Hubris, 
Phantom Dancer, 
Infinity Edge and 
Lord Dominik's Regards in that order, and takes 
Boots of Swiftness.
Three other builds are played often enough in the bot lane to be measured on their own.
In the bot lane, Jhin mains fare best against 
Ezreal (won 66.1% of 127 games), 
Smolder (won 78.9% of 19 games) and 
Viktor (won 65.5% of 29 games).
Their hardest matchups, the champions that counter Jhin, are 
Swain (won 26.3% of 19 games), 
Zeri (won 43.8% of 105 games) and 
Draven (won 44.3% of 88 games).