Hi @Anonymous ,
Could you please share a bit more about your scenario?
Do you want to show up the Border of the Text Input box when this Text Input Box is in Read-Only or Disabled?
Based on the needs that you mentioned, I have made a test, if you want to show up the Border of the Text Input box when this Text Input Box is in Read-Only or Disabled, I afraid that there is no way to achieve your needs.
When the Text Input Box is in View Mode or Disabled mode, the Border of the Text Input Box would disappear. If you would like this feature to be added in PowerApps, please submit an idea to PowerApps Ideas Forum:
https://powerusers.microsoft.com/t5/Power-Apps-Ideas/idb-p/PowerAppsIdeas
As an alternative solution, I think a Rectangle icon could achieve your needs. You could consider add a Rectangle icon in your app, set the BorderThickness property to following:
TextInput1.BorderThickness
set the Fill property to following:
RGBA(255, 255, 255, 1)
Then you need to move the Text Input box over the Rectangle icon as below:

Please take a try with above solution, check if it could help in your scenario.
Best regards,