I am an LPA for my father. There are two aspects to it - financial and health and wellbeing - so firstly you need to understand which your relative wants you to hold. Health and Wellbeing gives the power to take medical decisions on the person's behalf, e.g. you could decide to put them in a care home.
Also, are you to hold this in sole capacity or with someone else, and if someone else is involved, do you/your relative want you both to be able to act independently (jointly and severally).
There's a lot of form-filling to set it up, and then quite a wait in my experience for it to be registered.
Once you hold it, you have to make sure you can evidence anything you do with it is for the benefit of the donor (your relative). If he still has capacity and is acting for himself at the moment, there shouldn't be too much involved. If you need to act for him, you'll have to get the financial LPA registered with all his financial providers. A challenge my sister and I faced was actually finding out where all my dad's bank accounts were! Then you will need to keep evidence of any transactions so you can show they were legitimately for the donor's benefit.
I don't have experience of managing debt with a LPA - if my father has any, we haven't been able to uncover it. He had a couple of long-unused credit cards that we cancelled for security reasons, and that was a faff and a half, requiring registering for their online banking etc.
It is a big responsibility and particularly as this is a distant relative, it will be harder than it was for my sister and me and our dad, as we at least knew roughly where he banked, what his financial state was etc.
The background of family acrimony in your case is also something I would be wary of - is there a risk anyone might accuse you of misappropriating funds, for example? If you keep good records, that would be easy to disprove, but it would be unavoidably unpleasant. If it were me, I would feel more comfortable doing this jointly with another family member to minimise that risk.
In a nutshell, it's a lot of work for someone you don't have much of a relationship with - do you want to do take this on out of the goodness of your heart?
If no LPA is set up and he loses capacity, eventually someone will need to apply for Court of Protection for him - this is even more hassle and expense to set up than LPA as you have to get evidence of loss of capacity and pay court fees ( we did it for our mum) and then a similar situation managing it moving forward. So that is also something to bear in mind.
Wishing you luck whatever you decide.