Whilst we will look forward to One UI 5.1 will be incremental change, whilst no confirmed timetable should be rolling out to eligible Devices by March. Some information here https://www.sammyfans.com/2023/01/22/samsung-one-ui-5-1-update-news/
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .