$$ \mathrm {\color{white}\colorbox{#3486e7}{\Large~Fonts~}} $$

$\mathtt {Old~Typewriter}$

$\mathsf {Sans~Serif}$

$\mathbb {BOARD~uppercase}$$\mathrm {Elégant}$

$\mathcal {By~hand}$

\\mathtt {Old~Typewriter}

\\mathsf {Sans~Serif}
\\mathbb {BOARD~uppercase}
\\mathrm {Elegant}

\\mathcal {By~hand}

$$ \mathrm {\color{white}\colorbox{#3486e7}{\Large~Couleurs~}} $$

$\colorbox{aquamarine}{abc}$

$\color{white}\colorbox{cadetblue}{abc}$

$\color{#f82094}{abc}$

$\color{red}\fbox {abc}$

$\color{#FFFFFF}\colorbox{#f82094}{---(~}\colorbox{#3486e7}{a|b|c}\colorbox{#1c2db9}{~)---}$

\\colorbox{aquamarine}{abc}

\\color{white}\\colorbox{cadetblue}{abc}
\\color{#f82094}{abc}

\\color{red}\\fbox {abc}
\\color{#FFFFFF}\\colorbox{#f82094}{---(~}\\colorbox{#3486e7}{a|b|c}\\colorbox{#1c2db9}{~)---}

$$ \mathrm {\color{white}\colorbox{#f82094}{\Large~Sizes~}} $$

$\tiny {Tiny}$

$\scriptsize Script~Size$

$\footnotesize Footnote$

$\small Small$

$\normalsize Normal$

$\large Large$

$\Large Large$

$\LARGE Large$

$\huge Huge$

$\Huge Huge$

\\tiny {Tiny}
\\scriptsize Script~Size
\\footnotesize Footnote

\\small Small
\\normalsize Normal

\\large large

\\Large Large

\\LARGE Large

\\huge Huge

\\Huge Huge

$$ \mathrm {\color{white}\colorbox{#1c2db9}{\Large~Decorations~}} $$

$\utilde{Wave}$

$\underrightarrow{Arrow~to~right~~~}$

$\underleftarrow{~~~Arrow~to~Left}$

$\underline{Underline}$

$\overline {Overline}$

$\undergroup{1}~~\undergroup{2}$

$\sout{~crossed~}$

$\xcancel{Cancel}$

$\mathbb{\color{3486e7} {\Huge D}}$ropcap

\\utilde{Wave}

\\underrightarrow{Arrow~to~right~~~}
\\underleftarrow{~~~Arrow~to~Left}

\\underline{Underline}
\\overline {Overline}

\\undergroup{~~1~~}~~\\undergroup{~~2~~}

\\sout{~crossed~}
\\xcancel{Cancel}

\\mathbb{\\color{3486e7} {\\Huge D}}

$\def\arraystretch{2}\begin{array}{c:c|c||c}{lines}&{between}&{some}&{words}\end{array}$

def\\arraystretch{2}\\begin{array}{c:c|c||c}{lignes}&{entre}&{les}&{mots}\\end{array}

$$ \mathrm {\color{white}\colorbox{#f82094}{\Huge~A~Huge~text~centered~with~a~full~size~math~block~}} $$

\\mathrm {\\color{white}\\colorbox{#f82094}{\\Huge~~~A~Huge~text~centered~with~a~full~size~math~block~~~}}

$$ \mathrm {\color{1c2db9} \utilde{~A~centered~textwith~a~beautiful~wave~~~}} $$

\\mathrm {\\color{1c2db9} \\utilde{~~~A~centered~text~~with~a~beautiful~wave~~~}}

$$ \mathrm {\color{3486e7} \fbox{~A~text~with~a~border~}} $$

\\mathrm {\\color{3486e7} \\fbox{~~~A~text~with~a~border~~~}}

Source : https://notionthings.com/2021/01/23/advanced-notion-formatting-using-katex-expressions/