This is harder than it used to be. In the old days you could chat, get to know them, friend them on FB, etc. Now - everything is withheld before booking.
Before you "accept" the reservation you need more information. But any attempt to get it will be blocked. At one point we had a new user with no reviews who just signed up that day try to send her phone number. It kept getting erased by Airbnb. Even the names of her family coming with her (husband and son). So we traded phone number one post at a time. After talking on the phone we were laughing and sharing tips and we hosted her. It was three months into lockdown and she was going stir crazy living on a farm and wanted a place closer to the city for her young son to explore. She's now a friend. But it's stupid you have to find work-arounds for Airbnb's weird policy. You can't send them an email and Airbnb won't give you their data until they are booked (stupid, stupid, stupid). So proceed cautiously.
You could say you'll temporarily approve the request so you both can figure out if this is a fit. If not, the guest can cancel or you can within the first day at no penalty.
Long term guests can be wonderful. Or not. So far I've had good luck. But if they are asking to stay three months, explain you'll need them to sign a lease with agreements as to end date (which can be extended if you both wish it.) In many states more than 30 days give them tenants rights and you need to know who they are and why they are wanting to rent for 3 months.
Good luck.