Init.ora parameters in CDB / PDB

Hello
We are converting our non PDBs 19c database to a multi tenant architecture
We have a couple of questions on the init.ora settings related to that
Here are our current settings (non multi tenant) for some of the parameters
processes = 500
sga_target = 20G
sga_max_size = 30G
open_cursors = 1000
pga_aggregate_target = 10G
Assuming that we would have 2 PDBs in each container should we be making the changes
at ROOT / CDB$ level or at each PDB level for these init.ora parameters
And should the value in the CDB / ROOT container be the total of both values in each PDB?