Ok so i have a single speed road bike that I love but I live in Utah & know I won't be able to ride it in the winter. So this summer I plan on building a fixed/single speed bike suitable for Utah winters cause I want to start commuting year round. I'm looking to build from a Throne Bikes frame. Do you guys have any suggestions or tips how to build a bike like this?
I'm looking for ideas about:
-frames
-handle bars
-TIRES
-any other advice

Thanks!

don't build it on a throne for one.

what are utah winters like where you live? certainly park city winter is very different than slc winter.

if you deal with a fair amount of snow as I would assume, here's my list of advice:

the absolute best type of bike you could do this with is a single speed 29er, but ss 26" or 27.5" mtbs, or ss cyclocross bikes will do fine too. preferably a frame with lots of tire clearance, relaxed geometry, and disc brakes. despite the rust factor, I'd still recommend steel, the compliance makes riding over bumby ice sheets and unplowed roads a lot more comfortable. the larger the wheel diameter the better, even just six inches of fresh wet snow will make a 26" wheel stop dead. 29ers have a much better chance of rolling through it, and even that couldn't get through the worst of it here.

build it on a bike with clearance for at least 35mm tires, and get the burliest, knobbiest tires you can fit into your frame.

mountain bike riser bars, a nice upright position and wide cut bars (at least 600mm) will make for better stability and leverage on snow, ice, and slush.

fenders, self explanatory

water-resistant lower layers, your wheels will be kicking up a lot of wet gritty slush on the warmer days, even with fenders, your feet and legs will get wet, dress for it.

ride slow, ride ahead of yourself, and be prepared to go down occasionally - ice ruts will get you.

You're going to want wide-ish tires and possibly studded tires, for a start. You probably don't need fatbike tires just for commuting; think CX size. So you'll need a frame with clearance for those. I also highly recommend fenders, because at least where I live, winter commuting involves lots of sloppy, salty, brown slush in addition to the actual snow. So you'll want eyelets and clearance for those, too.
And you'll probably want a somewhat lower gear than you would in the summer, because you'll be grinding your way through snow wearing bulkier clothes in the wind, and if you're anything like me, your chain won't be running too smooth by the end of the season.
So you probably don't want super fancy pricey drivetrain components, either.

Other than that, it just depends on your preferences. I use the same bars for winter commuting as I do for road riding, because I like them. I commute on a Surly CrossCheck, which has room for fenders and reasonably wide tires, plus it has mounts for a rear rack, which I consider essential equipment for an around-town bike. It has short horizontal dropouts, which makes it work easily as a fixie. It has a durable powder coat and it's enough of a tank to survive life as a beater bike in New England. They are very popular around here for exactly that reason, although the CrossCheck is by no means the only frame that meets that description.

wait, the absolute best bike you could do this with isn't a ss 29er, that's the second best, the best is a fat bike. buy a fat bike, do it.