As far as illegals go on day one all you gotta do is enforce the law. The intent is easy. The action will take time.
Round ‘em up. Ship ‘em out. Guard the border. Shoot on sight. Not many bodies will accumulate before there will not be any need for a wall.
Don’t even have to deport them. Stop giving them free stuff and fine employers who hire them. They’ll know what to do.
We want that wall. We need that wall. Walls are apolitical and work 7x24x365. The next President may be a globalist squish. The Wall will work despite him (or her).