Hi there,
If this is a schematic or panel you first want to be sure you are using the correct library. The components in each library are scaled relative to their 'stanrd' as in everyone in the JIC library is to one scale and everyone in the IEC library is of another scale.
That being said, if it is a one time thing use the 'scale' tool to resize the block. Or you could use the 'block editor' tool to open the block, change geometry and save it. Or if it is a permanent change, you can go to the block file like HCR11.dwg, open it like any other drawing, do your edits and save it. If you do that be sure to use the 'purge' tool to remove it from old drawings before inserting the new block.
Just a few of about 102 ways to do it.
By the way, if you use the 'block edit' tool, select the block first then select the tool. That way the block will be selected when you open the tool. If you select the tool first you will have to select from a list of every block in the drawing.
Good luck
If you, for some reason, need to use symbols made in imperial units in a metric title block, these are the settings that controls the scale of the schematic symbols when you insert them:
