UEFA will hold a trial for a slightly different setup for penalty shoot-outs at the UEFA Under-17 finals and UEFA Women's Under-17 finals: https://www.uefa.com/under17/news/newsid=2463576.html?rss=2463576+Penalty+shoot-out+trial+at+UEFA+final+tournaments
Instead of teams alternating 1 penalty at a time the 1st team will take 1 penalty, the 2nd team will then take 2 penalties, then the 1st team will take 2 penalties, then the 2nd team will take 2 penalties and so on.
They're doing this because the IFAB has growing evidence that the team which takes the 1st penalty in every pair has an advantage.
Personally I wouldn't mind seeing this become a new rule.