BSC:

Network Name: Smart Chain
New RPC URL: https://bsc-dataseed.binance.org/
ChainID: 56
Symbol: BNB
Block Explorer URL: https://bscscan.com

Polygon:

Network Name: Polygon
New RPC URL: https://polygon-rpc.com
ChainID: 137
Symbol: MATIC
Block Explorer URL: https://polygonscan.com/