DENMARK - COVID-19. Update on 06/02/2021:
The Danish Ministry of Foreign Affairs discourages all unnecessary travel to Denmark from all countries of the world without distinction and also Danish citizens and residents of Denmark are strongly advised against any travel abroad, including those for business.
Access to the country is guaranteed only in the presence of a proven valid reason, as specified on the site regulations / entry-into-denmark

Some of the valid reasons provided are: work (but not work as an au pair), participation in legal proceedings, medical examinations, transport of goods, close family members of minors and seriously ill people, spouses, close family members or engaged couples of residents in Denmark, while study reasons are not recognized.
In addition, from 9 January until 28 February 2021 inclusive , all travelers flying to Denmark, in addition to a valid reason, must also present proof of a COVID-19 test negative (PCR or antigenic) carried out no later than 24 hours prior to the first boarding of the voyage with final destination in Denmark. In case of failure to present the aforementioned documentation, financial penalties and / or imprisonment up to two years are envisaged. This measure is also valid for Danish citizens and residents of Denmark but does not apply to passengers on domestic flights (including Greenland and Faroer) and to children under 12 years of age.
Foreign workers entering Denmark are required to carry out a second PCR test after 72 hours of arrival in Denmark, in addition to the test within 24 hours before departure.
Starting from Sunday 7 February , in addition to the already reported obligation to document a negative COVID-19 test carried out in the 24 hours preceding the start of the direct flight to Denmark or access by land in the country, an additional rapid test immediately upon arrival and a self-isolation period of 10 days are made mandatory , which can be reduced to 5/6 days, by undergoing another test at least 4 days after arrival in the country. A pecuniary sanction of 3,500 Danish crowns (about 450 Euros) is foreseen for offenders. These provisions do not apply to those residing in border areas and frontier workers.
In addition, some partial lockdown restrictions remain in effect across the country until February 28, 2021.

Answers from the Danish Ministry of Foreign Affairs and the Danish National Police to frequently asked questions regarding travel to Denmark can be found at this link