'lend gravity' is not correct and usable in written English.
You could use the phrase 'add gravitas', meaning to give something more weight or importance, in the same context. For example: His extensive experience in the field lent gravitas to his insights.
The mayor's comments appeared to lend gravity to a civil rights lawsuit by Internal Affairs Detective Jimmy Alvarez, an eight-year police veteran.
Historically, invocations have been utilized to lend gravity to the situation and are part of the nation's heritage.
The child mortality rate and other statistics contained in the report lend gravity to the basic United Nations assertion that serious investment in the rights and development of children is essential to overcoming poverty.
The natural heft and earthy colorings of his voice lent gravity to his portrayal.
Her gusto lent gravity to her lyrics, which were often about bridging emotional distances.
The truth is that one thing alone lends gravity to Bond, and tethers him down to our shared earth, and that is the actor who plays him.
Viola Davis and Maria Bello are convincingly wretched as the mothers who react to heartbreak in very different ways, while Melissa Leo lends gravity even as the narrative floats towards the lightweight.
It's the ancient-mariner baritone that lent gravity to the early Genesis, to Mr. Gabriel's 1970s and '80s hits like "Solsbury Hill" and "Sledgehammer," and to "Down to Earth," the Oscar-nominated song he wrote with Thomas Newman for the soundtrack of "Wall-E" in 2008.
The Canadian baritone has lately made a move into Wagner, singing Hans Sachs and Amfortas; the resultant darkening of his voice lent gravity and psychological complexity to the part of Tell, who makes his presence felt more through asides and responses than with bravura arias.
A steady adviser to the 2008 Obama campaign, he lent gravity to the young candidate's professions of competence in financial matters.
To lend additional gravity, veteran thesps Stephen Rea and James Fox play drug company shills entangled in the furtive goings-on.
