Well I wouldn't do all the BS ' don't do it', ' think of me , think of your family' , ' it gets better' etc. But I'd help them to explore other options first. I've tried different services, therapies, meds etc. before being sure of my decision to ctb. Just because they didn't help me doesn't necessarily mean it wouldn't help them. If they're willing and able, i'd help them access support first. I'd try to make sure that they've fully thought through their decision. Make sure it's not impulsive.
I wouldn't push them either way. But I couldn't step back and just go 'okay, it's your right, ctb' . Because sometimes when people tell someone they're suicidal , they're asking for help. I'd want to hear them out first, hear their reasons and if there's still some hope there then I'd help them explore that. Some suicidal people want help keeping safe, if they wanted that then I would. I'd keep them safe at home if that's what they wanted, would never force anyone into hospital/ask for them to be sectioned. But if they wanted to be admitted I'd support them ofc. I would do anything to help them live if they believe it's worth it.
However, i wouldn't force them to live a miserable life if they don't think it's worth it. If they're determined to die and no part of them wants help (or there's no help available) then I don't think there's anything i could do. I wouldn't want them sectioned and restrained just to physically stop them ctb without actually making their life worth living. That would be completely selfish. I would just make sure they don't feel alone and feel loved in the time they have left. And for them to know that i'm always there to help if they have a change of heart.