  High redshift quasars ($z>5$) that also shine brightly at radio wavelengths
are unique signposts of supermassive black hole activity in the early universe.
However, bright radio sources at $z\ge5$ are extremely rare and therefore we
have started a campaign to search for new high-$z$ quasars by combining an
optical dropout selection driven by the $g$, $r$, and $z$ bands from the Dark
Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys with
low-frequency radio observations from the LOFAR Two-metre Sky Survey (LoTSS).
Currently, LoTSS covers a large fraction of the northern sky (5720 deg$^2$) to
such a depth (median noise level of 83 $\mu$Jy beam$^{-1}$) that about 30% of
the general quasar population is detected $-$ which is a factor of 5-10 more
than previous large sky radio surveys such as NVSS and FIRST, respectively. In
this paper, we present the discovery of 20 new quasars (and the independent
confirmation of 4) between $4.9\leq z\leq 6.6$. Out of the 24 quasars, 21
satisfy the traditional radio-loudness criterion of
$R=f_{5\text{GHz}}/f_{4400A} > 10$, with the full sample spanning
$R\sim$6-1000, thereby more than doubling the sample of known radio-loud
quasars at $z \ge 5$. Our radio detection requirement strongly decreases the
contamination of stellar sources and allows one to select these quasars in a
broad redshift range. Despite selecting our quasar candidates using fewer and
less conservative colour restrictions, both the optical and near-infrared
colours, Ly$\alpha$ emission line properties, and dust reddening, $E(B-V)$,
measurements of our quasar sample do not deviate from the known radio-quiet
quasar population, suggesting similar optical quasar properties of the
radio-loud and radio-quiet quasar population at high-$z$. Our campaign
demonstrates the potential for discovering new high-$z$ quasar populations
through next generation radio continuum surveys.
