No it's not. But it is like a form of triggering, take Johnny Wilkinson's trademark pose before taking a kick on the Rugby field or Bruce Lee's scream, a Potterverse Wizard/Witches Patronus animal or Wand choice or a singer's face when they hit big notes.
It's the "harnessing and focusing" your Chi/Force concept and reflects the actual effort involved in a use of the force. Some find things extremely easy while others will find great effort reflected physically.
Someone like Vader can hurl objects and still "fight", this is because he was always "the chosen one" (had the highest Midichlorian count if you want to go that way) thus was stronger with the force... As Anakin his frustration was arguably a mental barrier, meaning he needed to use things like the hand gesture against Obi Wan. As Vader, with his Sith training "complete" he is not only more powerful but has no reservation or frustration holding him back, thus his force use is easier. The Dark Side is also likely inherently easier to use, it's part of the lure.
Likewise Luke can simply steeple his hands and use his Jedi mind trick while Obi Wan and Qui Gon had to use their hands to focus, despite him not believing his training complete. What isn't mentioned is Padme's level of Force "use", it's not a plot point but it's conceivable that as Queen of Naboo she'd have some level of Force affinity to be able to unite her people and is unusually perceptive.
As Anakin and Padme's offspring, Luke would arguably be the most powerful Jedi who ever lived. Mace Windu arguably had that distinction prior as his Force use was the most akin to Luke and Vader's, had he not died, conceivably he would have replaced Yoda as the leader on merit eventually.
Yoda, despite being the leader of the Jedi needed to use his focusing to lift Luke's X-Wing, possibly due to his age but also it may have been relative to his physical size.
Realistically though, no hand motion would be required but it would help the individual.