GM Companion note: Social interactions are guided by ability checks, player ingenuity, GM control, or a combination of these. (See PHB 186 and DMG 244) Circumstances and your character's identity play a large role in social interactions.
A Charisma check might arise when you try to influence or entertain others, when you try to make an impression or tell a convincing lie, or when you are navigating a tricky social situation. The Deception, Intimidation, Performance, and Persuasion skills reflect aptitude in certain kinds of Charisma checks. (82)
The GM might call for a Charisma check when you try to accomplish tasks like the following:
Find the best person to talk to for news, rumors, and gossip
Blend into a crowd to get the sense of key topics of conversation (83)
With respsect to social interactions, the GM can decide that circumstances influence a roll in one direction or the other and grant advantage or impose disadvantage as a result. (77) See also Aiding the Check (DMG 245), Parleying with Monsters (TCoE 148), and the charmed condition.
If an ability check is required, the GM determines the Difficulty Class (DC). See PHB 186 and DMG 244 for guidance.
Try roleplaying when interacting.
Your Wisdom (Insight) check decides whether you can determine the true intentions of a creature. (82)