"Personality" in a hiring context does not mean being extroverted, entertaining, or naturally charismatic. It means whether an interviewer, in a short conversation, comes away trusting that you'd be reasonable and pleasant to work with. That is a much narrower and more practisable thing than "personality" suggests.
A quiet, careful candidate who listens well, answers precisely, and is honest about gaps often comes across better than an outwardly confident one who talks over the interviewer or oversells. Being naturally reserved is not a disadvantage here — it just needs its own version of preparation rather than trying to imitate a different personality entirely.
The specific thing to avoid is not quietness — it is disengagement. Not asking a single question the entire interview, giving one-word answers with no elaboration, or showing no visible reaction to anything said reads as disinterest, whatever the actual intent behind it was.
For video calls specifically: look at the camera occasionally, not just the screen, since that is what reads as eye contact on the other end. Sit reasonably upright. A calm, steady presence communicates more than most people expect it to, and it is a habit rather than a talent — noticeable and correctable with a little practice in front of a camera beforehand.
Come across as someone paying real attention, answering honestly, and genuinely interested in the conversation. That single description covers most of what "personality" is actually being evaluated on in this context, and every part of it is something you can deliberately practise.