Hi Elamathi,
yes Floating label textbox is possible in mendix with custom styling ,
- create a textbox with out label by select show label no in General tab for Text Box
- create a Label above your text box and make label style class to match with the form-label
- add custom styling with focus and onhover stylings for the input element in theme sources -->your Module main.css
- customize your input and label styling classes with your custom styling class
done.