How to make an adjustable freeze pane line?

For work we use Microsoft Teams to communicate and edit files as a group. On Teams, there is an excel file that has a line that is adjustable that prevents scrolling for anything above that line. When I try to set that line up on my personal Excel files on my computer at home, there is no such thing and the internet doesn't believe it exists. i can freeze the pane at the row I want, but it can't be adjustable. There is not setting or google search that will help me set an adjustable freeze pane line.

Please help