Do you know at least what is the RLC buffer size?
I think it is 1Mb on most UEs.
I mean new UEs.
You can find it in UE capabilities the RLC buffer size.
May I ask why you want to know this?
It is probably 40% for activation of SCC and 5% for deactivation of SCC ,or some similar valuer, for a specific amount of time of course.