Hi @Hetvik ,
You can refer to my steps:
To upload attachments for a record, you can use Edit form. See my example. I have a gallery called "Gallery4" that shows all record of my dataverse table. Beside this gallery, I have a Editform that display the selected record of Gallery4. The current selected record called "test0812" with no attachment:

I can add attachments for this record using the Attachment control inside this Editform, then click submit button(SubmitForm(Form3)) to save the changes:

To read the attachments of the records, I can add another gallery in another screen, and set its Items property to:
Gallery4.Selected.Attachments

Note: Attachments returns table type result, even there is only one attachment, the returned result type is Table, so we need to use gallery to show the attchment.

Best regards,
Allen