Confusion about what Dijkstra one to many does

I’m using a custom weighting for routing and have run into some confusion about what the Dijkstra one to many algorithm does. Does it find only one path, or does it find all the possible paths and then select the best one?

My use case is to calculate all routes between the start and target node, and then select the one with the least total cost according to my custom weighting. I’m not sure if this is what Dijkstra one to many is for, or if I should be implementing my own algorithm.

One-to-many is from one node to many nodes.
What you want is one-to-one by the sound of it. Your custom weighting is applied during the dijkstra process - so it builds a single path that is the least cost for your weighting. You don’t need a separate selection phase.