Yes. It is the most common way families start, and nothing about it commits you or your parent to anything.
What does not happen
Your parent is not contacted. Nobody emails them, texts them, or mentions you signed up. That conversation is yours to have, in your own time.
No trial clock is running. Your fourteen days begin the day your loved one joins, not today.
Nothing is charged. You do not need a card to start.
You can look around for a week, decide this is not for your family, and disappear. Nothing will have happened.
What you can actually do meanwhile
Enough to decide properly:
Read the Family Hub guides, including the ones on bringing up a difficult subject with a parent
See what would be shared with you, and what would not
Work out what you would actually be asking her to agree to
That last one is the useful part. Arriving at the conversation having already understood the privacy model beats arriving with an app you want her to install.
When you are ready
Invite her. She creates her own account, holds her own login, and decides what she shares with you, category by category. It is her account, not a profile you manage on her behalf.
The fourteen days start then, and you both get the full fourteen together.
If she says no
That is a real answer and it happens. You will not be charged for a trial that never began, and nothing keeps prompting you.
Some families come back six months later, when something has changed. The account is still there.