how to start a long position by adding a percentage lower condition with Pine Script

I'm trying to figure out how to start a long entry with a percentage lower. For instance, when ema 20 crossover ema 50, the long entry will trigger only 1% lower than the pricelevel once the crossover happens.

you can use the limit paramater on the strategy.entry() function. This will set the max price you are willing to enter a long trade. In your case, we will set the max price to be 99% of the close price when the crossover happened.

//@version=5
strategy("My strategy", overlay=true)

ema20 = ta.ema(close, 20)
ema50 = ta.ema(close, 50)

longCondition = ta.crossover(ema20, ema50)
shortCondition = ta.crossunder(ema20, ema50)

if (longCondition)
    strategy.entry("Long", strategy.long, limit=close * 0.99)

if (shortCondition)
    strategy.close_all()

plot(ema20, color=color.green)
plot(ema50, color=color.fuchsia)