default or selected kernelversion does not have config value CONFIG_DEVPTS_MULTIPLE_INSTANCES.
Result is shown for kernelversion 6.5.1

Support multiple instances of devpts


Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Support multiple instances of devpts
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
Enable support for multiple instances of devpts filesystem.
If you want to have isolated PTY namespaces (eg: in containers),
say Y here. Otherwise, say N. If enabled, each mount of devpts
filesystem with the '-o newinstance' option will create an
independent PTY namespace.