Index: src/wp-content/themes/twentynineteen/sass/site/secondary/_widgets.scss
===================================================================
--- src/wp-content/themes/twentynineteen/sass/site/secondary/_widgets.scss	(revision 44431)
+++ src/wp-content/themes/twentynineteen/sass/site/secondary/_widgets.scss	(working copy)
@@ -1,6 +1,10 @@
 .widget {
 	margin: 0 0 #{$size__spacing-unit};
 
+	.widget-title {
+		font-size: $font__size-lg;
+	}
+
 	/* Make sure select elements fit in widgets. */
 	select {
 		max-width: 100%;
Index: src/wp-content/themes/twentynineteen/style-rtl.css
===================================================================
--- src/wp-content/themes/twentynineteen/style-rtl.css	(revision 44431)
+++ src/wp-content/themes/twentynineteen/style-rtl.css	(working copy)
@@ -3337,6 +3337,10 @@
   /* Make sure select elements fit in widgets. */
 }
 
+.widget h2.widget-title {
+  font-size: 1.6875em;
+}
+
 .widget select {
   max-width: 100%;
 }
Index: src/wp-content/themes/twentynineteen/style.css
===================================================================
--- src/wp-content/themes/twentynineteen/style.css	(revision 44431)
+++ src/wp-content/themes/twentynineteen/style.css	(working copy)
@@ -3343,6 +3343,10 @@
   /* Make sure select elements fit in widgets. */
 }
 
+.widget .widget-title {
+  font-size: 1.6875em;
+}
+
 .widget select {
   max-width: 100%;
 }