To add a Search for Blog Posts, you can follow these.
#1. Install Filter Plugin
#2. Open the Filter Documentation Page, you will see a code line like this. Copy it.
#3. Open Blog Page > Click the Gear icon
#4. Click Advanced > Page Header Code Injection
#5. Paste the code you copied in #2.
#6. You will see a Get Filter Config button. Click it.
#7. Click Copy Code
#8. Replace #5 code with the code you just copied in #7. You will have something like this.
#9. Result
#10. To remove the Category dropdown, you can remove the code between red ( )
#11. To remove the Sort dropdown, you can change true to false
#12. If the Tag dropdown still appears, you can remove the code between red ( )
#13. Result