--snip--
The same applies to offline cold storage PC as well? If the system is not connected to internet.
Yes, internet usage is just one of many entropy source.
Then also there will be enough sources of entropy right?
Yes (assuming it's not headless or embedded device). But if you have
very very very serious security concern, just run this command and make sure the value is either 256 (Linux kernel 5.10.119 or newer) or 4096 (Up to 5.10.118)[1].
cat /proc/sys/kernel/random/entropy_avail
[1]
https://unix.stackexchange.com/a/704743