diff --git a/esphome/core/color.cpp b/esphome/core/color.cpp
index 58d995db2f..7e390b2354 100644
--- a/esphome/core/color.cpp
+++ b/esphome/core/color.cpp
@@ -2,10 +2,8 @@
 
 namespace esphome {
 
-const Color Color::BLACK(0, 0, 0, 0);
-const Color Color::WHITE(255, 255, 255, 255);
-
-const Color COLOR_BLACK(0, 0, 0, 0);
-const Color COLOR_WHITE(255, 255, 255, 255);
+// C++20 constinit ensures compile-time initialization (stored in ROM)
+constinit const Color Color::BLACK(0, 0, 0, 0);
+constinit const Color Color::WHITE(255, 255, 255, 255);
 
 }  // namespace esphome
diff --git a/esphome/core/color.h b/esphome/core/color.h
index 1c43fd9d3e..2b307bb438 100644
--- a/esphome/core/color.h
+++ b/esphome/core/color.h
@@ -5,7 +5,9 @@
 
 namespace esphome {
 
-inline static uint8_t esp_scale8(uint8_t i, uint8_t scale) { return (uint16_t(i) * (1 + uint16_t(scale))) / 256; }
+inline static constexpr uint8_t esp_scale8(uint8_t i, uint8_t scale) {
+  return (uint16_t(i) * (1 + uint16_t(scale))) / 256;
+}
 
 struct Color {
   union {
@@ -31,17 +33,20 @@ struct Color {
     uint32_t raw_32;
   };
 
-  inline Color() ESPHOME_ALWAYS_INLINE : r(0), g(0), b(0), w(0) {}  // NOLINT
-  inline Color(uint8_t red, uint8_t green, uint8_t blue) ESPHOME_ALWAYS_INLINE : r(red), g(green), b(blue), w(0) {}
+  inline constexpr Color() ESPHOME_ALWAYS_INLINE : raw_32(0) {}  // NOLINT
+  inline constexpr Color(uint8_t red, uint8_t green, uint8_t blue) ESPHOME_ALWAYS_INLINE : r(red),
+                                                                                           g(green),
+                                                                                           b(blue),
+                                                                                           w(0) {}
 
-  inline Color(uint8_t red, uint8_t green, uint8_t blue, uint8_t white) ESPHOME_ALWAYS_INLINE : r(red),
-                                                                                                g(green),
-                                                                                                b(blue),
-                                                                                                w(white) {}
-  inline explicit Color(uint32_t colorcode) ESPHOME_ALWAYS_INLINE : r((colorcode >> 16) & 0xFF),
-                                                                    g((colorcode >> 8) & 0xFF),
-                                                                    b((colorcode >> 0) & 0xFF),
-                                                                    w((colorcode >> 24) & 0xFF) {}
+  inline constexpr Color(uint8_t red, uint8_t green, uint8_t blue, uint8_t white) ESPHOME_ALWAYS_INLINE : r(red),
+                                                                                                          g(green),
+                                                                                                          b(blue),
+                                                                                                          w(white) {}
+  inline explicit constexpr Color(uint32_t colorcode) ESPHOME_ALWAYS_INLINE : r((colorcode >> 16) & 0xFF),
+                                                                              g((colorcode >> 8) & 0xFF),
+                                                                              b((colorcode >> 0) & 0xFF),
+                                                                              w((colorcode >> 24) & 0xFF) {}
 
   inline bool is_on() ESPHOME_ALWAYS_INLINE { return this->raw_32 != 0; }
 
@@ -169,9 +174,4 @@ struct Color {
   static const Color WHITE;
 };
 
-ESPDEPRECATED("Use Color::BLACK instead of COLOR_BLACK", "v1.21")
-extern const Color COLOR_BLACK;
-ESPDEPRECATED("Use Color::WHITE instead of COLOR_WHITE", "v1.21")
-extern const Color COLOR_WHITE;
-
 }  // namespace esphome
diff --git a/esphome/core/time.cpp b/esphome/core/time.cpp
index 672f5b98bf..f9652b5329 100644
--- a/esphome/core/time.cpp
+++ b/esphome/core/time.cpp
@@ -226,11 +226,11 @@ int32_t ESPTime::timezone_offset() {
   return offset;
 }
 
-bool ESPTime::operator<(ESPTime other) { return this->timestamp < other.timestamp; }
-bool ESPTime::operator<=(ESPTime other) { return this->timestamp <= other.timestamp; }
-bool ESPTime::operator==(ESPTime other) { return this->timestamp == other.timestamp; }
-bool ESPTime::operator>=(ESPTime other) { return this->timestamp >= other.timestamp; }
-bool ESPTime::operator>(ESPTime other) { return this->timestamp > other.timestamp; }
+bool ESPTime::operator<(const ESPTime &other) const { return this->timestamp < other.timestamp; }
+bool ESPTime::operator<=(const ESPTime &other) const { return this->timestamp <= other.timestamp; }
+bool ESPTime::operator==(const ESPTime &other) const { return this->timestamp == other.timestamp; }
+bool ESPTime::operator>=(const ESPTime &other) const { return this->timestamp >= other.timestamp; }
+bool ESPTime::operator>(const ESPTime &other) const { return this->timestamp > other.timestamp; }
 
 template<typename T> bool increment_time_value(T &current, uint16_t begin, uint16_t end) {
   current++;
diff --git a/esphome/core/time.h b/esphome/core/time.h
index 5cbd9369fb..a53fca2346 100644
--- a/esphome/core/time.h
+++ b/esphome/core/time.h
@@ -109,10 +109,10 @@ struct ESPTime {
   void increment_second();
   /// Increment this clock instance by one day.
   void increment_day();
-  bool operator<(ESPTime other);
-  bool operator<=(ESPTime other);
-  bool operator==(ESPTime other);
-  bool operator>=(ESPTime other);
-  bool operator>(ESPTime other);
+  bool operator<(const ESPTime &other) const;
+  bool operator<=(const ESPTime &other) const;
+  bool operator==(const ESPTime &other) const;
+  bool operator>=(const ESPTime &other) const;
+  bool operator>(const ESPTime &other) const;
 };
 }  // namespace esphome