For example, I wanted to replace the values stored in the “enabled” field of P1 feature class with their corresponding values stored in “enabled-Sc” filed stored in J1. What tools might do this sort of thing effectively and efficiently within the capacity of model builder knowing that there is a common field between the stand-alone table (J1) and the attribute table (P1).
Your above ModelBuilder setup looks correct for what you want to do. However this setup will not append the joined data to the "enabled" field. Instead it will add the Enabled_Sc field to the P1 table.
The easiest method of appending the data to the Enabled field would be to drag the "calculate field" tool into ModelBuilder, using your join output as the input and changing the expression to Enabled = Enabled_Sc (there is a graphical builder in that tool which makes it easy to chose the correct fields).
Then you can remove the joined field Enabled_Sc from P1 with the "remove join" or the "delete field tool" leaving the updated values in the Enabled column.