Basically all 3D software has plane drag handles in additional to orthogonal drag handles in the translation tool.
Observe the colored squares on this image:
They are colored to the perpendicular axis color. For example, the ZY handle is red because it is perpendicular to X.
Dragging one of these squares will drag the object along a plane, similar to dragging on a line with the orthogonal handle but in two directions at once.
Roblox should add these plane handles to the translation tool.
Here’s a video demonstrating the difference between orthogonal handles and plane handles. Observe that the YZ handle can drag on both the Z and Y axes at once.