The Biden-Harris Inauguration event begins at 11am EST/8am PST. It'll be carried by all of the expected news broadcasters, on TV and most likely on their webpages too. There's lots and lots of online streams that will be covering it too, even Amazon Prime will have a stream.
If all else fails, here's (one of) the YouTube stream:
Of course there will be some ceremonial things at first. Lady Gaga will be singing the National Anthem around 11:30. The swearing-in will take place just after noon local.
Some TV broadcast networks may play their own relevant pre-programming before the official event starts, you'll have to check that for yourself. A kids' program called "Our White House: An Inaugural Celebration for Young Americans" will
begin streaming at 10am on YouTube before the main event.
Finally, tomorrow night, from 830pm to 10pm ET, Tom Hanks will be hosting "Celebrating America", basically a virtual concert show with a bunch of stars. It will be carried by most if not all channels and websites that carried the Inauguration itself earlier that afternoon.