Capital Gains into another Property

[Clay Couvillon]

Hello BP family, my very first post and interaction on here.  I hope this works, this is actually for my brother, he is looking to sell a rental property and wants to avoid paying capital gains.  Does he have to use those profits into a new Investment property, or could he use part of into an existing property to gain a little more equity into it.  We are also in Houston TX, not sure if it differs per state.