or with jq:

$ jq -rn --arg x 'pa//ssw[]r()d{}' '$x|@uri'
pa%2F%2Fssw%5B%5Dr%28%29d%7B%7D
$

from https://gist.github.com/sergeiwaigant/f0cf816e143114b6a7d81a901b5d3ce6

or even simpler using xxd and sed (from the same source):

$ echo -n 'pa//ssw[]r()d{}' | xxd -p | sed 's/../%&/g'
%70%61%2f%2f%73%73%77%5b%5d%72%28%29%64%7b%7d
$

works in alpine based python images, the debian based ones do not have xxd installed (yet)