What happens if the eighth Lord Jupiter is placed in the 3rd house Libra with Rahu and Venus?

From the information provided, the individual is a Leo Ascendant

• Jupiter-Rahu-Venus in 3rd House (Zodiac of Libra)
• Jupiter rules the 5th(Zodiac of Sagittarius) & 8th(Zodiac of Pisces)
• Venus rules the 3rd(Zodiac of Libra) & 10th(Zodiac of Taurus)
• The 5th & 8th houses signify Kids, Talent, Past Life Karma, Death-Rebirth(Transformation), Life after marriage, Joint Assets
• The 3rd & 10th houses signify Communication, Friends, Younger Siblings, Profession

Now coming to a few observations that can be made from this:

1. The placement of Jupiter in Libra makes it uncomfortable. Despite this, Jupiter bestows its blessings in the areas controlled by the lord of the house – Venus
2. Through this placement, Venus will exert more control over the houses that Jupiter rules(5th & 8th)
3. Rahu tends to amplify aspects of the Jupiter-Venus conjunction
4. As the 3rd house is 6th from 10th, the individual will face obstacles at their work place & career progression. The wisdom of Jupiter will be helpful here
5. As Mars is the Yoga Karaka of the Leo Ascendant(Lagna), its placement and aspect of the houses linked to Jupiter or Venus will be crucial

Hope this helps

God Bless!