It’s rare to have a client like this but it happens. Sometimes a client will try to manipulate or bully you into doing something you are not comfortable with or something you know will not be nice or heal nice. You need to refuse the client. Clients like this will most likely become a problematic client in the future.
If this client is really pressuring and bullying you into giving them something that is against your recommendation you can write a note on their consent form and have them sign off on it that they want to get something against their recommendation. Usually, if you simply suggest this to your client, they will back off since this is a sign that you are seriously not recommending that option. Typically when I say this to my client, they will stop bullying me because they’ll realize I’m serious and that if anything goes wrong that it is not my fault.