Solid Hardwood, Engineered and Laminate Flooring - Painting OLD wood floor

My son and daughter-in-law just bought a 100+ house. The livingroom and diningroom have old wood floors with "good" wood around the perimeter and lower quality wood in the center where a rug would cover it. The floor has been painted off-white (a long time ago obviously) and the wood joints have separated and it's chipped in many areas. I would like to help them paint it brown, but unsure on how to proceed since we don't know what kind of paint is on it, and don't want to sand because of lead exposure. Any ideas? Thanks!

Have the paint tested, if you are leary of messing with it.

But to answer you other question, the protocol for painted wood floors, is the same for a snd and finished wood floor. The difference being the coating used(paint vs. clearcoat)

Seal it and paint it red or green, it will be correct with the time period of the home