Demo account is not accurate because execution is instant or much faster than in live account that's why demo performance, especially decent returns of some scalping strategies is difficult to replicate on real account.
Leverage, in my opinion, should be used only when you know what you're doing and have a solid trading strategy. After opening a live trading account, beginners should avoid using leverage right away.
when i was a beginner in trading i used no leverage in trading but right now beginners use too much leverage and at the end of the day they become loser.