Wat Pho has a huge Buddha- the reclining Buddha.
It’s fun to take someone visiting Bangkok to see the reclining Buddha and watch for their “oh damn, that is a big Buddha” look. The bottom of the feet are great- inlaid mother of pearl images.
Wat Pho is always swamped with tourists, but this is a must see. Try going at off peak hours- if you can stand the heat, visit in the late afternoon. Don’t miss the murals on the walls around the reclining Buddha, some cool paintings.