At this age you might be trying to socialise toddler with other children, but this will still be problematic. She's just not particularly sociable yet at this age, especially with children, and will still prefer to play with familiar adults such as parents, aunts and uncles, and other caregivers such as nannies or nursery nurses. However, if they are in regular contact with another toddler then it is possible they could develop a friendship and only fight with them every -other- day!
Acting up and tantruming at the worst possible times is quite common around now. Be reasonable in what you expect from them, and remember they're still getting to grips with their emotions versus their independence. Everything you do keep your toddler in mind and how their mood can change - visits from polite company, and trips out to quiet places should ideally be kept short to stop her becoming bored and then disrupting everything for other people.
Birthdays of children who are now 21 months old are from Thursday 28 Jan. 2021 through Saturday 27 Feb. 2021.