Keep keyboard open when lost focus by clicking background canvas - TextMeshPro Input Field

I have a form that contains a few input fields. I want to scroll down the UI while the keyboard is open. UI has a canvas and it’s scrollable. But when I touch the canvas while the keyboard open, the keyboard will close due to lost focus. I found a few related questions but can’t achieve this. If anyone knows how to achieve this behaviour, please help me.

I’m using TextMeshPro input fields

Platform - Android and iOS.
@alnovlucky

I believe you can manually set the focus of UI elements in Unity by using an eventsystem. This used to be easier in WinForms (C# Windows application tools) where you can use the method GetFocus(), however in Unity, this is done by, I believe, EventSystem.current.SetSelectedGameObject(yourGameobject); or UIElement.Select()