It’s not a good idea for a number of reasons.
1. Doing your own extracts can be fun, but at the end, you have no idea as to the concentration of active ingredients - unless you pay a LOT to have it analysed, and may cost more in the end than buying products off the shelf.
2. “Bar soap” - do you mean cold or hot process soap? If so, the high pH degrades most organic materials very rapidly.
3. Some essential oils can destabilise saponified products or reduce their stability over time.