Square Symbol    Square Name                                         Decimal    Hex

■                Black Square                                     ■ ■
□                White Square                                     □ □
▢               White Square With Rounded Corners                ▢    ▢
▣               White Square Containing Black Small Square       ▣    ▣
▤               Square With Horizontal Fill                        ▤    ▤
▥               Square With Vertical Fill                        ▥    ▥
▦               Square With Orthogonal Crosshatch Fill           ▦    ▦
▧               Square With Upper Left To Lower Right Fill       ▧    ▧
▨               Square With Upper Right To Lower Left Fill       ▨    ▨
▩               Square With Diagonal Crosshatch Fill                ▩    ▩
▪                Black Small Square                                 ▪ ▪
▫                White Small Square                                 ▫ ▫
◧               Square With Left Half Black                        ◧    ◧
◨               Square With Right Half Black                        ◨    ◨
◩               Square With Upper Left Diagonal Half Black       ◩    ◩
◪               Square With Lower Right Diagonal Half Black      ◪    ◪
◫               White Square With Vertical Bisecting Line        ◫    ◫
◰               White Square With Upper Left Quadrant            ◰    ◰
◱               White Square With Lower Left Quadrant            ◱    ◱
◲               White Square With Lower Right Quadrant            ◲    ◲
◳               White Square With Upper Right Quadrant            ◳    ◳
◻               White Medium Square                                ◻    ◻
◼               Black Medium Square                                ◼    ◼
◽              White Medium Small Square                           ◽ ◽
◾              Black Medium Small Square                           ◾ ◾
⚿               Squared Key                                        ⚿    ⚿
⛋               White Diamond In Square                            ⛋    ⛋
⛝               Squared Saltire                                    ⛝    ⛝
⛞               Falling Diagonal In White Circle In Black Square    ⛞    ⛞
⛶               Square Four Corners                                ⛶    ⛶
⛾               Cup On Black Square                                ⛾    ⛾
❏               Lower Right Drop-shadowed White Square            ❏ ❏
❐               Upper Right Drop-shadowed White Square            ❐ ❐
❑               Lower Right Shadowed White Square                ❑ ❑
❒               Upper Right Shadowed White Square                ❒ ❒
⟎               Squared Logical And                                ⟎ ⟎
⟏               Squared Logical Or                                ⟏ ⟏
⟤               White Square With Leftwards Tick                    ⟤ ⟤
⟥               White Square With Rightwards Tick                ⟥ ⟥
⧄               Squared Rising Diagonal Slash                    ⧄ ⧄
⧅               Squared Falling Diagonal Slash                    ⧅ ⧅
⧆               Squared Asterisk                                    ⧆ ⧆
⧇               Squared Small Circle                                ⧇ ⧇
⧈               Squared Square                                    ⧈ ⧈
⧉               Two Joined Squares                               ⧉ ⧉
⧠               Square With Contoured Outline                   ⧠    ⧠
⧮               Error-barred White Square                       ⧮    ⧮
⧯               Error-barred Black Square                       ⧯    ⧯
⬒               Square With Top Half Black                       ⬒    ⬒
⬓               Square With Bottom Half Black                   ⬓ ⬓
⬔               Square With Upper Right Diagonal Half Black       ⬔    ⬔
⬕               Square With Lower Left Diagonal Half Black       ⬕    ⬕
⬚               Dotted Square                                   ⬚    ⬚
⬛               Black Large Square                              ⬛ ⬛
⬜               White Large Square                              ⬜ ⬜
⬝               Black Very Small Square                           ⬝    ⬝
⬞               White Very Small Square                           ⬞    ⬞
⯀               Black Square Centred                              ⯀ ⯀
⯐               Square Position Indicator                      ⯐ ⯐

All this is taken from: https://www.alt-codes.net/square-symbols