Yii2 add LIKE condition with "%" wildcard on the one side

You can use:

Table::find()->where(new \yii\db\Expression('name LIKE :term', [':term' => $_GET['q'] . '%']));

or

Table::find()->where(['like', 'name', $_GET['q'] . '%', false]);

or

$likeCondition = new \yii\db\conditions\LikeCondition('name', 'LIKE', $_GET['q'] . '%');
$likeCondition->setEscapingReplacements(false);
Table::find()->where($likeCondition);

More info at https://www.yiiframework.com/doc/api/2.0/yii-db-conditions-likecondition

You need set the fourth operand to false in order to use custom where like conditions:

Table::find()->where(['like', 'name', $_GET['q'] . '%', false]);

From the docs:

Sometimes, you may want to add the percentage characters to the matching value by yourself, you may supply a third operand false to do so. For example, ['like', 'name', '%tester', false] will generate name LIKE '%tester'.