how to change thickness of borders

Hi,
Welcome to the forum.
Select the range where you want to apply the border, rt click, select "format cell" - "border" or Home - border- more borders, from border style you can select the border style as per your requirement ie thick thin etc. and apply by clicking outlines or inside, you can also see the preview.

Plz see the attachment, i have illustrated with printscreen

Glade, it helped you. That is the max thick line available.
if that solves your problem plz click on the * to add to my reputation,
and mark the thread as solved.
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