Let's say it's a Warn XD9000 (only because it's what I have and I have data). You look at the current drawn under your expected use under average and peak load. You also have to make an assumption for duration at each step.

Peak load is obviously what it takes to get unstuck. It won't be the full rating of your winch necessarily but you have to be realistic. Say you have a small truck (I have a Tacoma) that weighs 5,350 lbs. To require that from your winch would require trying to actually lift it off the ground completely. But say you are badly bogged and that is what's needed as a worst case. So 5,350 lbs and you don't have a lot of line unspooled so I'd estimate I need 375 amps for 10 seconds to break it free.

Average load is something less since you're not usually bogged in clay mud over your tires on a 45° slope. So normally your pull force is much less, say 2,250 lbs (about 50% of a mid size truck perhaps, which is still a pretty decent pull), and you have most of your line unspooled and thus just say 185 amps for 2 minutes.

FWIW, this is the generalized way to calculate force required.

You'd next want to consider wire size and insulation. With a given current and time you can calculate the temperature rise of the conductor. The normal way to size fuses is based on the conductor diameter and insulation temperature rating. You want a fuse that opens before the wire.

You're thinking 1/0 AWG using 105°C EPDM welding cable. In this case my calculations say 375 amps will cause it to reach 105°C in a 40°C ambient (starting point and environment are important) in 218 seconds. Asking it to carry 185 amps will raise it from 40°C to 105°C in approximately 894 seconds and 56 amps will take hours (163 minutes).

The next step is to look at time-current curves for the protective device you're considering. Overcurrent devices are specified using time-current curves such as this. You look at the current you need to hold (e.g. operating current) and the current you want to open the device plotted against the time you need for each.

These are for the Littelfuse Mega.

https://www.littelfuse.com/products/fuses/automotive-aftermarket-products/bolt-down-fuses/mega.aspx
Sometimes they just state it directly, such as the case with those little MRBF we like to hang right on the terminals.

https://www.waytekwire.com/datasheet/MarineRatedBatteryFuse.pdf
So the thing most people do is say "I want to open at 375 amps so I'm going to buy a 375 amp fuse." This is not the way to size fuses. A 375 amp fuse will HOLD 100% (e.g. 375 amps) indefinitely and will allow significantly more for quite some time.

You don't want that. In my hypothetical I only need 375 amps for 10 seconds, 185 amps for 120 seconds and 56 amps forever. So a better size fuse for a XD9000 in my example might be 225 amp rated. Using an MBRF type that means it will hold 225 amps for at least 100 hours, 304 amps for 900 seconds and 450 amps for 60 seconds.

In the case of an accident that shears and shorts the cables (e.g. the dropping the wrench scenario) it'll open 788 amps within a second, which is far sooner than the wiring or battery start to become a problem. A 1/0 AWG carrying 788 amps will take about 39 seconds to go from 40°C to 105°C.

Note also that I have not derated anything for temperature. A fuse or circuit breaker is rated for a nominal ambient environment and going up or down changes it's performance, which makes selecting the right value for a vehicle additionally difficult. So I might actually select 250A or 300A for derating and margin.

Point here is it's a system where you balance load, cable size and fuse characteristics to achieve what you want. Putting a 400 amp fuse on a XD9000 may actually be a false sense of safety even on 1/0 AWG cable. You'd need probably a 4/0 AWG to carry 400 amps indefinitely.