This is where you should set your hours in slack to show you are unavailable.Overall I'm pro work from home/remote work for many reasons, one of which is I think it's better to have highly paid workers spread out across the country rather than centrally focused in a single small area.
One negative I've noticed is the boundary between work hours and personal hours has been blurred to the point where for many it no longer exists, it was already deteriorating before but I think it has really ramped up now. Everyone is sending slack messages at all hours of the day and the expectation is you have to engage because other people do it. I think Poland have recently enacted laws that prevent bosses from sending people slack messages after work hours, other countries should adopt the same.
Or you can work with HR to get 1-2 hours+ extra on each check in a bulk time format for responding to items off the "normal" clock.
Otherwise set your hours and it will auto notify people. Businesses who are large do not necessarily like always on demand slack messages because it increases liability for unpaid work off the clock. Being SENT messages is not the issue... Having to reply though? That needs to be or should be outlined in your salaried packet or not allowed if hourly and not on call.