Hi @Sanjay V welcome to the Atlassian community.
Below that issue types, their must be an option to add a new field to be dispalyed (for your reference: screenshot below which is very old from Atlassian documentation)
If that option is not there, then probably you need to confine to the existing fields.
Stay safe and stay healthy.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.