5 Watt is plenty to be heard. A more important question is, when are you trying to make contact?

I don’t know your experience level, so make sure that you’re doing this when the band is noisy, not when it’s quiet, especially on 40m.

Also make sure that you are aware of solar storms and geomagnetic disturbances, but if you can hear others, that’s a great start.

Think of making contact as flyfishing, it takes patience and practice!

Good luck.