Cypress family giant such as Cryptomeria or Sequoiadendron - closer view needed to be more specific. Even if a comparatively small growing garden selection these are already too tall to be in proportion with that narrow bed.

Looks like Cryptomeria to me.

Cryptomeria. Planted too close to hydrangeas.

Cryptomeria can grow quite tall (>50 ft). And while it can live in Zone 6, you run the risk of rare cold outbreaks doing some damage. I had one growing decently in zone 5 Indiana until the winters of 2013 and 2014. Killed it back to nearly the ground. Most good conifer hedges won't stop at 15-20 ft. However, perhaps a holly would work well? Unfortunately you are a little too cold for Burford and Nelly Stevens, which would be perfect for what you are wanting.