From the picture given, there is still some skin laxity seen.
Firstly, for the type of HIFU treatment that you did, what was the recommended number of sessions? This is because some HIFU treatments require more than 1 treatment e.g. monthly treatment x 3 sessions to see the full effect.
Secondly, how long ago was the HIFU done? This is because for HIFU treatments that only require 1 treatment session, it typically takes 3-6 months to see the full effects.
Thirdly, botox is not the right treatment for saggy cheeks if you're referring to botox of the masseters. In fact, that may worsen the jowling or saggy cheeks.
However, besides HIFU, other treatments that can be done for saggy cheeks include:
1. Dermalift
Thir procedure uses microdoses/diluted doses of botulinum toxin which are injected intradermally(not intra-muscularly) along the facial contours. This results in skin tightening and improvement of skin laxity along the facial contours.
2. Thread lift
This minimally-invasive treatment uses dissolvable threads which are inserted into the subcutaneous layer of the skin with anchoring, creating an instant lifting effect. It also stimulates collagen production which in the long run, is beneficial for skin lifting and rejuvenation.