@Thadeusz-Lay don't think there are hooks to do that. You can accomplish it by adding some js and css in ACP -> Appearance -> Custom HTML & CSS.
Here is an example. You will need to add code to handle what needs to happen on clicking the button.
Custom Header:
<script type="text/javascript"> $(document).ready(function() { $(window).on('action:ajaxify.end', function(ev, data) { $('[component="account/cover"] .avatar-wrapper').append('<button class="btn-new"><i class="fa fa-plus"></i></button>'); }); }); </script>Custom CSS:
.avatar-wrapper .btn-new { height: 2em; width: 2em; line-height: 2em; border-radius: 50%; border: none; background: #F44336; color: #fff; overflow: hidden; top: 93px; left: 4px; position: absolute; }
