What the OP meant was swapping the network from ETH to BSC or to Matic for example on certain DEXs because not all DEXs have that feature and I don't think the cost is that much either because some DEXs cut costs from the coins themselves or from the coins swapped to another network.
So this is what is called a bridge between networks, That's probably what the OP meant.
I've used the bridge platform several times, and in fact the fee will be much higher because the fee is needed on both networks.