I wasn’t confident that would work, sometimes you just have to try stuff and see what works.
What you might need to do is use Get Style to get the width and height
${wdth}= Get Style //*[@id=select-weightage] width
${hght}= Get Style //*[@id=select-weightage] height
divide the height by 2 and the width by 100 (you might have to play with these numbers to allow for offsets). then use Click With Options and use the position_x and position_y to click at a point along the slider that matches the percentage you want
@damies13 Since am trying via browser library unable to do like you mentioned. However i found this keyword
Drag And Drop Relative to id=select-weightage 80 steps=1
and using this able to move the slide but not to the desired value.