Try a full screen mode appear animation

edit-post/assets/stylesheets/_animations.scss

@@ -26,6 +26,11 @@
 	animation: slide_in_right 0.1s forwards;
 }
 
+@mixin slide_in_top {
+	transform: translateY(-100%);
+	animation: slide_in_top 0.1s forwards;
+}
+
 @mixin fade_in($speed: 0.2s, $delay: 0s) {
 	animation: fade-in $speed ease-out $delay;
 	animation-fill-mode: forwards;

edit-post/assets/stylesheets/main.scss

@@ -37,6 +37,12 @@
 	}
 }
 
+@keyframes slide_in_top {
+	100% {
+		transform: translateY(0%);
+	}
+}
+
 // In order to use mix-blend-mode, this element needs to have an explicitly set background-color
 // We scope it to .wp-toolbar to be wp-admin only, to prevent bleed into other implementations
 html.wp-toolbar {

edit-post/components/fullscreen-mode/style.scss

@@ -14,4 +14,11 @@ body.is-fullscreen-mode {
 	#wpfooter {
 		margin-left: 0;
 	}
+
+	// Animations
+	@include fade_in(0.3s);
+
+	.edit-post-header {
+		@include slide_in_top();
+	}
 }