Editing an image to make the outline more bold

You could scale it up to 200%, run the Minimum filter, and scale it back down to 50%. You could skip the scaling, but I think it makes the results look nicer.

You have several options:

1. Copy the fox layer and set its blend mode to Multiply.  This will move any pixels not already full black, towards full black, but it won't  make the lines thicker
2. Paint over the fox with a brush set to Overlay.  This will have a similar result to #1
3. There is only one truly viable approach to take, and that is to rebuild it as a Vector Object.  It's your brand for goodness sake, and it says a lot about your company.  As a vector graphic you will have total control over line thickness, colour etc.  You can use it any size and it will remain totally clean and smooth.  Combine the fox graphic with the text, and make  it a Smart Object, and drag it to a Library. It will be instantly available going forward.  It's an hours work for any half proficient graphic artist.