Definitely can be done, need them in fresh and pooled up though not running up etc. Dark days are best, these fish are very light sensitive more than steelhead I think.

Sinktips and streamers or speys, nymphs also dead drifted or worked as a streamer will work at times.

Caught my first king on a fly in 1981.

10 wt rod at least for these beasts.

Have fun.

FL