Single Family Dwelling.
What say you on service size? Al SE
Does the MAIN say 100 amp? If so you would need a minimum of #2 AL.
Is that what you are asking?
I say 100 AMP Service. I’ve not seen anything less tha 200 AMP on a SFD dwelling in a very long time. Between the SE and main breaker it seems wrong for a place built in '96.
What do you think?
It’s hard to say without doing a load calculation. Around here there are many houses with 100 amp services, although for the most part heating, cooking, hot water etc, are done with natural gas.
If that CB at the top right is the main the NEC would require a retention clip or some other device to permit its use as a back-fed breaker.