Actually that’s an example of a soft fork. When you change the rules to make them more restrictive (add limits, decrease block size, block addresses, etc) those

Actually that’s an example of a soft fork. When you change the rules to make them more restrictive (add limits, decrease block size, block addresses, etc) those running the old version will find the new blocks valid so will try to build on them and find their blocks to be rejected, but can keep running no problem and are incentivized to upgrade. When you change the rules to be less restrictive (add operations, increase block size, etc) then any old version will reject the new blocks, so will keep running their own chain until they are upgraded, potentially forever if there’s demand.