I think there is some truth in what you have been told. If people don't take the advice on social distancing seriously, there may be a lock down and punishments for flouting it.
If you are self-isolating because you are at high risk, rather than social distancing, that is a different matter. You have to assess the situation carefully and decide what is best for you.
For now it seems plot and park visits are legal, but that may alter very fast if circumstances change.