I tried this code but it produced the line too long and I couldn’t find an ability within the plot function to shorten the length of the line to the desired effect

//@version=5
indicator(title="Time points", shorttitle="Tp", overlay=true)
UTCTimeInput = input('1807-1808', title="Dam") 
OpenValueTime = time("1", UTCTimeInput)
var OpenPA = 0.0
if OpenValueTime
    if not OpenValueTime[1]
        OpenPA := open
plot(not OpenValueTime ? OpenPA : na, title="time point", color=color.black, 
linewidth=2, style=plot.style_linebr)

I tired calling line.set.xy1 and xy2 as per below but it didn’t plot anything.

indicator(title="Time Points", shorttitle="TPs", overlay=true)
starttime = time('1807')
endtime = time('1901')
var float priceLevel = na
if (time >= starttime and time <= endtime)
    priceLevel := open
var line horizontalLine = na
if (na(horizontalLine) and not na(priceLevel))
    horizontalLine := line.new(starttime, priceLevel, endtime, priceLevel,
color=color.black, width=2)
else if (not na(horizontalLine))
    line.set_xy1(horizontalLine, starttime, priceLevel)
    line.set_xy2(horizontalLine, endtime, priceLevel)