No cucumbers do not ripen once they've been picked off the vine.
If you've picked cucumbers from the vine before they ripened then they are as ripe as they'll get and no amount of waiting will improve the ripeness of cucumbers.
So if you have cucumbers growing you need to wait for the cucumbers to ripen fully before picking them because they will not ripen anymore.
All cucumbers that you buy in stores or at farmers markets etc should be fully ripened because they only pick the cucumbers when they are fully ripe and ready to eat.
Cantaloupes and even watermelons will not ripen anymore either once they've been picked just like cucumbers will not ripen.