[Yes, you'd be granted several forks such as Bitcoin Cash, Bitcoin SV and Bitcoin Gold on a 1:1 ratio.
As long as you sweep them into a compatible wallet (i.e. that support those forks), you could retrieve them.
If having the forked coin, he can just import the private key on a compatible wallet which will make the forked coins appear and spendable but bitcoin was sent to the wallet in 21018, all those cryptocurrencies forked before 2018 aside bitcoin SV, which means only bitcoin SV is likely to be seen if he sent bitcoin to the wallet before bitcoin SV forked in November 2018.