A JKR Pottermore writing says Sir Cadogan had a Muggle job.
Sir Cadogan, the knight whose portrait hung in Hogwarts, was said to have had a Muggle job. His only mentioned job was being a knight (perhaps a Knight of the Round Table), and he’s also armored like a knight would be in his portrait, so presumably that means that being a knight was considered a Muggle job.
Before the wizarding community was forced into hiding, it was not unusual for a wizard to live in the Muggle community and hold down what we would now think of as a Muggle job.
It is widely believed in wizarding circles that Sir Cadogan was one of the famous Knights of the Round Table, albeit a little-known one, and that he achieved this position through his friendship with Merlin. He has certainly been excised from all Muggle volumes of King Arthur’s story, but wizarding versions of the tales include Sir Cadogan alongside Sir Lancelot, Sir Bedivere and Sir Percivale.
Sir Cadogan (Pottermore)
He did seem to be still using magic despite not having a wizarding job, since he’d taken his wand with him to battle the Wyvern of Wye, and it bit his wand in half - likely meaning he had it out so he could use it in the battle.
Sir Cadogan’s most famous encounter was with the Wyvern of Wye, a dragonish creature that was terrorising the West Country. At their first encounter, the beast ate Sir Cadogan’s handsome steed, bit his wand in half and melted his sword and visor. Unable to see through the steam rising from his melting helmet, Sir Cadogan barely escaped with his life. However, rather than running away, he staggered into a nearby meadow, grabbed a small, fat pony grazing there, leapt upon it and galloped back towards the wyvern with nothing but his broken wand in his hand, prepared to meet a valiant death.
Sir Cadogan (Pottermore)
However, his job itself wasn’t magical in nature.
Another writing says Armand Malfoy had a non-magical job.
According to a different writing on Pottermore, Armand Malfoy was part of the invasion led by William the Conqueror.
Like many other progenitors of noble English families, the wizard Armand Malfoy arrived in Britain with William the Conqueror as part of the invading Norman army. Having rendered unknown, shady (and almost certainly magical) services to King William I, Malfoy was given a prime piece of land in Wiltshire, seized from local landowners, upon which his descendants have lived for ten consecutive centuries.
The Malfoy family (Pottermore)
While he most likely used magic in his job, he would have worked among Muggles, and presumably worked in the service of a Muggle (there’s nothing that indicates William the Conqueror was a wizard).
This also implies it’s less common after the Statute of Secrecy.
The Pottermore writing on Sir Cadogan says that before the wizarding world was forced into hiding (therefore before the Statute of Secrecy) that it wasn’t unusual for wizards to live among Muggles and have a Muggle job. This implies that, conversely, after the wizarding world was forced into hiding, it became somewhat more unusual for wizards to live among Muggles and have Muggle jobs. (This doesn’t mean it’d never happen, just that it’s less common after the Statute of Secrecy was implemented.)