Can an old phone be used as a reliable burner phone if I wipe its data?

I have an unlocked phone (Samsung Galaxy S9), and I no longer use it. I was thinking of wiping it so I can use it as a burner phone with a new service line paid for with cash. I mostly work with certain populations that I want to protect my identity from.

Will wiping an old phone actually keep me secure? Does a 5 year old phone like S9 have security weaknesses that make it not worth using?

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