Indeed, direct access via the menu and property inspector have been removed for several versions now.
If you want to use floating elements and/or absolute positioning (AP), you'll have to do so in code. It's not very complicated, and you'll find good explanations on MDN https://developer.mozilla.org/fr/docs/Web/CSS/position.
Beware, however, that a common error is that elements positioned Absolute are positioned in relation to their first explicitly positioned parent. For this reason, it's often usual to position the referent container with a Relative position, which doesn't vary its position in the flow, but provides a defined anchor for the child block to be positioned abolutely.