If you cannot toggle Ignore/Include options (note: you can do this by left-clicking the actual option captions, also), this is because you have not yet expanded that folder, so Pro has not yet enumerated the contents of it (because if we are copying 'everything', there is no need to remember all the separate contents - we just record the equivalent of * to mean 'include everything').
But, if it does not yet know the detailed contents, it cannot make a record of them to know what represents 'now' and then determine what is 'new' later on unless you expand it. So you need to expand the folder level you want to set Ignore options for (so that the files and/or sub-folders inside it are visible/enumerated) before the options are activated. You can then select the appropriate options for that level. You can collapse its view afterwards if you want.
This is mentioned in the contextual Help on that dialog, which I suggested you read, by the way...
But, if it does not yet know the detailed contents, it cannot make a record of them to know what represents 'now' and then determine what is 'new' later on unless you expand it. So you need to expand the folder level you want to set Ignore options for (so that the files and/or sub-folders inside it are visible/enumerated) before the options are activated. You can then select the appropriate options for that level. You can collapse its view afterwards if you want.
This is mentioned in the contextual Help on that dialog, which I suggested you read, by the way...