Can overbite be fixed without braces?

Possibly. Technically, "overbite" refers to how much your top teeth cover your bottom teeth. "overjet" refers to how far your top teeth stick out in front of your lower teeth (see photo). An overbite is a common bite problem. There are now many treatment options. Depending on the severity of your overbite, invisalign or other clear aligner technology may successfully correct your bite.
Yes, but... I assume you are talking about horizontal overbite (over jet, buck teeth). Orthodontic specialists have many treatment modalities at their disposal, but some work better than others. Regular braces (metal or clear) work better than inside braces which work better than clear aligners, for example. Have a qualified orthodontist check you out. You'll be glad you did.
Probably. Clear aligner treatment like invisalign might be an option. The only way to determine if clear aligner treatments are appropriate for your individual situation is to make an appointment for an evaluation with an orthodontic specialist.
Sometimes. Wheter or not the correction of your overbite can be treated with or without braces depends on the severity of your overbite, the diagnostic skills, expertise, and experience level of your dentist. Some dentists may elect to treat your bite problem without braces, and others would refer you to an orthodontist.