file: /proc/sys/net/ipv6/conf/interface/max_addresses
variable: net.ipv6.conf.interface.max_addresses
Official reference

Maximum number of autoconfigured addresses per interface. Setting to zero disables the limitation. It is not recommended to set this value too large (or to zero) because it would be an easy way to crash the kernel by allowing too many addresses to be created. Default: 16

disable_ipv6 - BOOLEAN Disable IPv6 operation. If accept_dad is set to 2, this value will be dynamically set to TRUE if DAD fails for the link-local address. Default: FALSE (enable IPv6 operation)

When this value is changed from 1 to 0 (IPv6 is being enabled), it will dynamically create a link-local address on the given interface and start Duplicate Address Detection, if necessary.

When this value is changed from 0 to 1 (IPv6 is being disabled), it will dynamically delete all address on the given interface.

Nb: per interface setting (where “interface” is the name of your network interface); “all” is a special interface: changes the settings for all interfaces.