If the address isn't yours (I mean you don't own its private key) and there isn't any transaction made from that address, there is no way to find the public key of the address.
You can't derive public key from the address. The address is derived from the public key through a one way function.
If there's a transaction made from the address, you can find its public key by checking the transaction details in a block explorer.
If the address is P2PKH (legacy), the public key is the second part of Sigscript.
If the the address is P2WPKH (native segwit) or P2WPKH-P2SH (nested segwit), the public key is the second part of witness.
Here is the sample address: 1N45DoSuhiNi5dCqMTpC2k3tfSaHEw1uKk
Since no transaction has been made from this address, there is no way to find its public key.
To know the public key of this address, you need its private key.