Are there any coins that are backed by multiple assets?
Some are afraid of bitcoin's high volatility, others are not happy about
stable-coins' low volatility, are there any coins "in the middle" that are
backed by a basket of assets?
For example, is there a coin backed by Fiat (say USD), Bitcoin and Gold?
What would be the effects of having a crypto "in this format" ?
It seems that you want some kind of hybrid coin, but the question is why do you want something they that? As far as I know that doesn't exist, but it defeats the whole purpose of having a decentralized currency, now you're going to have to rely on a centralized institution to have as much fiat, bitcoin and gold in hand to back all the coins that they create.
And while this may seem like a good idea I disagree because we have seen in the past many coins that were supposedly backed by gold and all of them failed.