I was up there a few weeks ago.
Everyone wears a mask all the time up there, even outside on the sidewalk although there is not specific law requiring it. You do have to wear them on the subway and other public transit (Federal Law) and I think you have to wear it indoors at museums.
Some restaurants will ask you to provide proof of vaccination or they will not seat you.
My recommendation is do as the locals do and be prepared to wear a mask. DC got hit hard with the Omicron variant, you wont get much sympathy if you go up there with the attitude that you're going to be an asshole about not wearing the mask.