

It still exists. We may not lobotomize patients or put them in insulin comas, but forced ECT is still on the table. Even if the practice has improved with technological advancements, it can still be misapplied.
Though it was almost a decade ago (and in Austrailia) this story stuck out to me as being an example of everything that can go wrong in psychiatry: https://www.madinamerica.com/2016/05/psychiatry_garth_daniels/
It’s fucking tragic.
If they are actively violent and have committed a crime, hold them until their (expedited) court date (while providing them the option to explore support/therapy and/or access to spiritual counselors), record examinations by psychiatrists/perform them with outside/impartial observation, give the accused legal representation, and let publicly observable courts decide their fate. The option of a jury, witness/family/etc. testimony, and second opinions is imperative to their human rights.
If they have committed no crime (homelessness or being unable to provide for your needs are not crimes), are not violent, and are not a direct threat to themselves or others (and there is no concrete evidence that they will be) - there’s nothing you should be able to do to violate their will.
In the latter situation, the best you can do is try to earn their trust and ensure they are provided an environment where they feel safe - providing them with every social support and alternative that they should be entitled to explore for their betterment.