Sure! The keyword to look for is "DHCP-PD" (DHCP prefix delegation).

I run a little OpenBSD router and my dhcpcd.conf is here [1], but I've done this before on a Linux router box too -- here are some instructions from Arch's wiki [2]. IIRC, the stock firmware on my old consumer router was also able to request a prefix and advertise it on the network.

[1] https://gist.github.com/cfallin/e5865a6a93c75ace8d26d6a85287... [2] https://wiki.archlinux.org/index.php/IPv6#Prefix_delegation_...