There's a Bangkok Post article dated 25 October 2023 entitled "HSBC Thailand taps global connectivity", which talks about them growing their asset management business here to better serve their HNW clients. It sounds as though they may have asset management operation, specifically for HNY clients.
I think their wealth/asset management services in Thailand are provided only to their corporate HNW customers, not to private HNW individuals...
"HSBC is committed to its goal to be the best bank and a key driving force for the Thai economy and Thai society.
Today, HSBC provides a comprehensive range of financial and banking services to corporate customers".
https://www.about.hsbc.co.th/hsbc-in-thailand
I'm happy to be corrected if you know specifically otherwise.