My brother's mental health is quickly deteriorating - please help

Yes it's actually my brother. For context he is 32 and has a history of addiction. 5-6 years ago he became addicted to cocaine and adderall to the point where I had a psychotic break (thinking people were following him, accusing my Dad of putting super glue in his mouth as he slept). He was diagnosed with stimulant psychosis, went to outdoor rehab, and got sober. For the the last 5 years he has been doing much better, or at least that's what our family thought. He moved and got a job we thought he liked.

8 months ago he abruptly quit his job and moved back with my parents. Within the last couple months he started having acute panic attacks. His delusions and paranoia have also been re-emerging, this time in the absence of drug use. He did recently admit that he smoked weed a couple times, and he tried ketamine therapy a few months ago to treat what he thought was PTSD (he won't talk about whatever it was that caused this PTSD). But since his panic attacks started he's acknowledged that these drugs weren't helping and stopped again. But his delusions and paranoia have reached an all-time, frightening high. This week he got so angry at my dad for apparently "controlling him" that he charged and pushed him on the ground. Last night he told my parents he wouldn't talk to them, from behind inside his car, without the presence of police who can recognize his sovereignty as a free individual. This morning, my mom made him breakfast and he told her he wasn't going to eat anything with poison in it and that my mom only "looks like my mom". He texted me something along the lines that my parents are trying to make him schizophrenic. He's frequently accused my dad of being a spy in the last few weeks.

Since the panic attacks he's been put on Lexapro and gabapentin, with xanax as needed for acute situations (prescribed by a family doctor, not a psychiatrist). He has expressed willingness to work on his mental health but seems to be convinced he has "PTSD" or some underlying anxiety disorder, and does not acknowledge his paranoia or delusions. He has spoken with a psychiatrist and, from what we know, has been trying to schedule an appointment. But he did this once before and canceled his appointment because he didn't "trust the psychiatrist".

As of this morning, my parents have called 988 and requested an emergency mental health crisis response team to the house to take him in for an evaluation and hopefully be put on some kind of antipsychotic.

We don't know if he has bipolar or something else, I'm just hoping to get some insights from you all about this. This is something completely outside of the expertise of anyone in our family and it's been extremely sad and distressing, especially for my parents who have to deal with it daily. Is there any hope he can live a normal live if put on the right medication? Or that he can come back to the brother/son that we know?