There is no single answer to your question -- it depends on the lawyer and the question itself. Some lawyers will speak with any prospective client on the phone while others will require that they come in for a meeting. Some charge for an initial meeting and some do not.
In terms of the nature of the question, lawyers are much more likely to answer a general question about the law than a specific question about the prospective client’s situation. There are at least two reasons for this. First, without a full discussion of the person's situation, the attorney may give the wrong answer. Second, even if the attorney is not paid anything, answering a specific question could be considered creating an attorney-client relationship, which would make the attorney responsible for providing accurate legal advice and subject to claim if the advice turns out to be wrong. So, attorneys generally are reluctant to give specific advice without being formally engaged by the client.
Whatever the situation, the attorney or law firm should inform the client of any charges to anticipate. Here is an example of how it works in one elder law firm: The firm will talk with a prospective client over the phone. As discussed above, the firm will not provide specific advice during this call but will answer more general questions. The firm charges $500 for an initial, in-person consultation. The client has no commitment to pay anything beyond that unless the firm and the client agree on what work needs to be done and what the charge will be.
For information on why it is a good idea to use a lawyer for long-term care planning, go here: https://www.elderlawanswers.com/why-you-should-use-a-lawyer-for-medicaid-planning-16269.