For some families with very young children, the pandemic has been difficult. If you are staying mostly at home or going out less than you would have if there were no pandemic, here are some ideas.
Also, there are things you can do at home to give young children enrichment and social skills. Books open whole new worlds to them.
Build
structure into their lives. Have a place to eat meals. Maybe sit down together
at the table most evenings to eat dinner. Of course, now and then a picnic
outside might be fun, too. And I'm not saying anyone should have a strict
schedule, just that some routine is helpful for their wellbeing.
Establish some boundaries in their lives. You probably wouldn't let your child of 3 or 4 run inside of a church or at the library. But if you're not going out much, it might be harder to teach those kinds of boundaries. Is there an area of your home which would be safer for them if they don't run? That would be a good place for teaching the skill of respecting boundaries, such as "walking only" in this area.
And one more thing I would suggest is teaching them to come when you call them. Maybe they want to keep playing, but it might be helpful at some time - maybe even vital for their safety - if they learn to come when you call them to find out what it is you want. And then, at least some of the time, they can go back to their play.