Sun in the 6th house may not be the best placement for it in the ascendant chart since the 6th house is a Dusthana where a naturally malefic planet (Saturn, Mars, Rahu, and Ketu) will perform better.
However, Sun will still give the person good wealth, reputation, and an overall high position, but unless aspected by a benefic planet, the Sun in this case will also make the person very famous to enemies, meaning he/she will have many enemies who could cause him/her discomfort and problems. Additionally, the Sun, if under any malefic effects, will give diseases pertaining to the eye and vision, too.
Some conditions to note here are:
- Sun in its own sign (Leo) – this is a rare occurrence where Sun will gain strength to fight enemies of the native and the native will not be bothered or troubled by their rivals. Additionally, the Sun will also give good benefits to the native health-wise and financially.
- Sun in exaltation (Aries) – another excellent placement for Sun which enables the natives to defeat their enemies even if they may have too many of them. The native will also be emotionally resilient and healthy overall and will earn fame and reputation through their efforts.
- If the lord of the 6th house is weak (except if Sun is in its own sign or exaltation) – this will actually be good for Sun because when the lord of the 6th house when weak will also cause the malefic effects of the house to be reduced.
- Sun aspected by a benefic planet – the native will enjoy good health and also have fewer enemies or will be able to defend himself/herself from all of them.
*In the above two situations, I have seen that Sun in Leo in the 6th house is often more powerful or beneficial for the native as opposed to Sun being in its exaltation. Also note that when it comes to aspects or conjunctions, the Sun will be able to provide good results to the native if He is aspected by or is conjunct with a benefic planet. Alternatively, if the Sun is posited alone in the 6th house, He will still be able to provide good results even if aspected by a malefic if He is either (1) in his own sign, or (2) in exaltation.