The public can get on the Mall at the Inauguration but I’m not sure how far away they will be from those in the ceremony. There is security everywhere - local and state police, National Guard, helicopters (maybe even drones, who knows). I’ve even heard that there are snipers positioned on rooftops in strategic positions.
I’ve heard that the one thing that makes security nervous is when the President gets out of the limo during the parade and starts walking around. They’d rather he and his family stay within the heavily armored SUV on their way to the viewing platform.
I was in DC once and we were sight seeing and security chased us away cause the president was coming.
Now mind you, we were not even CLOSE to the White House but we were close enough to see tiny black figures on the roof of the White House that were holding what looked like high powered rifles.
And those were the ones we SAW. I'll bet there were plenty of others we missed.
So yes, the snipers are stationed on the rooftops.