u/Future-Plan-6072

I've seen mostly newer siennas in here but im hoping someone has had some experience in this. I purchase a used sienna with 190k havent had any issues, but I noticed the transmission fluid is dark. I dont know any of the maintenance records, should I drain/fill with new filter or leave it alone. I've seen some people say leave it alone and others have said just to drain/fill. 2011 3.5l AWD Thank you