I have now got a 2 entry tourist visa in my homeland (DK). When I arrive in Thailand by plane can I still get the 30 days visa exemption as I have got earlier and then make a border run 30 days later to activate the first entry of my tourist visa. I'm planning to stay +6 months in LOS.

If you have a valid visa immigration will want to use it under current policy.

Use the 1st 60days on entry, when it nears the end of that 60 days stay, get an extension at immigration for 30days 1,900 baht. before that 30days expires, do a border run and then start the 60days and 30days over again, that will give you about 180 days here.

have a great time