The basics are:
1. Make a selection from the text layer Layer -> Transparency -> Alpha to Selection
2. Make a new transparent layer for the outline.
3. Grow the selection by a suitable amount. Select -> Grow This depends on the Font and Image size.
4. Stroke the selection to make the outline Edit -> Stroke selection
However, your image shows that a little bit of distortion has been applied (deliberately or accidentally) You might/might not want to add another couple of steps
This series of images showing the process.
text and selection from text https://i.imgur.com/xKaiQAm.jpg
distort settings & Selection filled https://i.imgur.com/4WRZnaR.jpg
grow the selection & Stroke the selection https://i.imgur.com/lldH3Jn.jpg
1. Make a selection from the text layer Layer -> Transparency -> Alpha to Selection
2. Make a new transparent layer for the outline.
3. Grow the selection by a suitable amount. Select -> Grow This depends on the Font and Image size.
4. Stroke the selection to make the outline Edit -> Stroke selection
However, your image shows that a little bit of distortion has been applied (deliberately or accidentally) You might/might not want to add another couple of steps
This series of images showing the process.
text and selection from text https://i.imgur.com/xKaiQAm.jpg
distort settings & Selection filled https://i.imgur.com/4WRZnaR.jpg
grow the selection & Stroke the selection https://i.imgur.com/lldH3Jn.jpg