Across 926 ranked games on patch 16.21 in Master and above, Xayah mains win 56.6% of their games in the bot lane.
Their most common build appears in 36.9% of those games and wins 56.1% of its 342 games.
It starts 
two Health Potions and 
Doran's Bow, completes 
Yun Tal Wildarrows, 
Infinity Edge, 
Lord Dominik's Regards, 
Navori Flickerblade and 
Bloodthirster in that order, and takes 
Berserker's Greaves.
Three other builds are played often enough in the bot lane to be measured on their own.
In the bot lane, Xayah mains fare best against 
Ezreal (won 76.2% of 21 games), 
Draven (won 78.6% of 14 games) and 
Kai'Sa (won 65.2% of 46 games).
Their hardest matchups, the champions that counter Xayah, are 
Jhin (won 50.9% of 55 games), 
Varus (won 44.4% of 18 games) and 
Miss Fortune (won 47.4% of 19 games).