@Ruduen
I mean the renaissance era has something very similar to a suit.
And sure, they did not use ties... but it's not that big of a stretch considering they used some fluffy white napkin for a similar purpose.
I'm talking about a nobleman outfit, but considering he works for kings he should have been well paid...
Neckties became common in Europe in the 17th century, so its a bit later than most sword and magic settings, but it's ultimately just a fashion choice and could have become popular whenever.
Plate armour like the knights are wearing is something that became common around the 15th century if I'm not wrong.
So again, not a huge stretch to imagine people wearing ties for fashion in a fantasy world where plate armour is a thing.
Also, you could always use the argument that magic fucks up the timeline for better or worse when it comes to technological innovation.
Why invent a complicated, expensive and hard to build a heating system when you can just use fire magic to do the same "for free"
Why invent an electric pump when you can just fill a water tower with water made from magic and let gravity do all the work for you?