There are the standards for any large city. Museums. If you like basketball the Mavericks. There are a couple Sea Life Aquariums, one in grapevine and one in Fort Worth. I like Ripleys. There is the Texas Live venue near the ballpark in Arlington. You can take tours of Cowboys stadium, maybe the ballpark Rangers play in. Not sure on that though during off season. There is a place in grapevine that has an indoor water park, great wolf lodge I think. There is an ice sculpture exhibit in grapevine this time of year if you can handle the cold. Galleria has lots of shopping. Trying to think of things to do that are unique to the area that you could not do in any big city.
6 Flags is open on weekends. I think they have a sleigh ride on fake snow or used to.
Answers might change if you were coming in spring or summer. I tend to hibernate during the winter weather so most of what I like is summer oriented. There is an outstanding Japanese garden in Fort Worth at the botanical gardens. If you are in to flowers there is also a large botanical garden in Dallas. Zoo in both Dallas and Fort Worth.
Might google dallas tourism. That highlights the Arboretum. If you are in to history there is the Sixth Floor Museum downtown. You can go in and see where Oswald took the shot from. This time of your in highland park area you can take buggy ride to look at Christmas lights.
Go to visitdallas.com for more ideas. tripadvisor will also have a lot of information and travel guides you can download. And you might consider visiting
https://dallascityhall.com/Pages/tourism.aspx in prep for coming to Dallas.