Hello Nguyen Chinh Dat - TT DLPT,
Welcome to the Microsoft Q&A forum.
Unfortunately, Purview doesn't support adding more columns in the schema section of the data asset other than the default six columns, as shown in your screenshot.
I would recommend submitting this in the Purview feedback channel. https://feedback.azure.com/d365community/forum/1219ec2d-6c26-ec11-b6e6-000d3a4f032c
PG actively monitors and reviews all the feedback shared in this forum, which will prioritize them accordingly based on the number of requests.
Also, please share the link once the feedback is posted so that we can pass the feedback to respective product owners for further review.
I hope this info helps.