It is possible with some pre-requisite checks.
1. Steerer ID meets the compatibility requirements for the Threadless carrier (Min ID: 24.25mm)
2. Steerer does not neck internally at any point. You can check this by running a straight edge down & against the internal wall of your steerer. If it deflects then it necks and is not compatible.
3. Steerer is within our compatible length range. 185mm-265mm
4. Your current Top cap will need to replace the 1-1/2 plug supplied with our Threadless carriers. So check that the top cap fits flush without rocking, in the underside of the fork steerer.
If you can confirm all of these requirements are good then you should have no issue installing our threadless carrier in your straight steerer fork.