I haven't heard anything like that.
You might reference Texas Property Code
You might ask them to show you that provision in the Property Code as you are not familiar with it.
Or show you where it is in the lease?
I think you should give them a reasonable accommodation. However an extra 90days might not be reasonable...a day or 2 or 3 might be reasonable if there is some valid reason....like the apartment where they are moving needs time to build a ramp to accommodate a wheelchair. If they have lived in your property 12 years, giving them another week to me might be reasonable in this instance. I'm not sure you have to do this, but seems reasonable if there was ever a lawsuit.