Can I smear mud on wall to get antique look?

Please elaborate

Karen do you mean German Smear or dry wall mud? Could you give us some more details so we can help?

I found a YouTube video that might be what you're looking for...

https://youtu.be/gW2w8hzLn8k

Think twice about this. I have highly textured plaster walls at my mom's 1926 house. They get dusty quickly and are a pain to clean. If you want to do a light texture, here is how!

https://youtu.be/CKeXQRSjk_M

https://www.thespruce.com/how-to-texture-your-walls-452819

https://www.thespruce.com/hide-flaws-with-stipple-texture-4121027

https://www.bobvila.com/articles/how-to-texture-walls/

Really hard to repair fix any damage to these type of walls to get it to match up we have them in our house also hard to keep clean

Unless the plaster is very deeply textured, this type of wall is easily vacuumed with brush attachment and washes easily with soft cloth, but of course dust in the Eastern part of the U.S. may be substantially less that that in other parts of the country.