Youtube.. What would you do?

So I found some abandoned channels with many videos of my niche, domain listed in description and watermarked.. some are 5+years with no activity... 50+ videos

I have already registered the domains

my question is:

Is it better to try to rank them with links views and likes

or

download them, add some intro , reupload and try to rank???

what would you do

I would try to optimse what's already there.
Title, thumbnail, description etc.
It's probably less work than adding intros to it which will have no effect on it's ability to rank high.

but I have no access to those channels, I only got the expired domains in the description and watermarks

You can optimize what is already there if you want to.