*** a/wp-content/themes/twentynineteen/style.css
--- b/wp-content/themes/twentynineteen/style.css
@@
 /* --------------------------------------------------------------
 5.0 Blocks
 -------------------------------------------------------------- */
 
+/**
+ * Fix: Classic Editor right-aligned, uncaptioned images inside <p>
+ * should extend (bleed) beyond the content column like other right-aligned elements.
+ * See: https://github.com/WordPress/twentynineteen/issues/688
+ */
+@media screen and (min-width: 768px) {
+	.entry .entry-content p > img.alignright,
+	.entry .entry-summary p > img.alignright {
+		/* Ensure the image can exceed the paragraph's max-width */
+		max-width: none;
+		height: auto;
+
+		/* Keep it floated right, but let it bleed outside the text column */
+		float: right;
+		/* Pull image to the right by half the leftover viewport width outside the content column */
+		margin-right: calc((100vw - 100%) / -2);
+
+		/* Maintain the default spacing on the left so text wraps nicely */
+		margin-left: 1.5em;
+	}
+
+	/* Avoid overflow clipping on the paragraph wrapper in certain browsers */
+	.entry .entry-content p:has(> img.alignright),
+	.entry .entry-summary p:has(> img.alignright) {
+		overflow: visible;
+	}
+}
+
 /* Group */
 .wp-block-group.has-background,
 .wp-block-group__inner-container.has-background {
 	padding: 1.25em 2.375em;
 }