Summary
taking all brand guidelines into account, for uniform sizes use at least:
Minimum 29x29 pixels for the logo
Minimum margin of half the logo width z.B. 15 pixels on each side (=padding of 7.5 pixels)
LinkedIn:
Download: brand.linkedin.com/content/brand/global/en_us/index/downloads
Guidelines:
brand.linkedin.com/content/brand/global/en_us/index/visual-identity/logo
Modern download/guidelines (not necessarily preferred, use judgement):

- The logo must be the original shape as supplied or the website. It may not be displayed as a circle, square or other shape.
- The must be accompanied by a ™ symbol, so long as it is at a size where the ™ symbol would be legible. For email purposes that is not necessary. Only use the ® instead of ™ if the content is a post on the official linkedin website
- The logo must be surrounded by free space on all sides equal 2𝑥, where 𝑥 is the width of the ‘i’ in the logo.
- Minimum 21x21 px, not including ™/® symbol
- If using the ™ or ® symbol, do not place directly to the left of instagram icon, as this may break instagrams ‘free space’ requirement. All other brand icons are ok.
X:
Download:about.x.com/en/who-we-are/brand-toolkit
Guidelines:cdn.cms-twdigitalassets.com/content/dam/about-twitter/x/brand-toolkit/x-brand-guidelines.pdf


- The logo must be black on white or white on black (#000000/#FFFFFF)
- It must be clear and legible
- The free space must be equal on all sides (no minimum given)
- When pairing text with the logo, it must be scaled to the height of the x
Instagram:
Download: about.meta.com/brand/resources/instagram/instagram-brand/
Guidelines:about.meta.com/brand/resources/instagram/icons/

- Free space must be at least one half of the icons size on all sides.
- Minimum 29x29 pixels
- Use the “glyph”, do not use the “app icon”
Facebook:
about.meta.com/brand/resources/facebook/logo/

Free space must be at least one quarter of the icons size on all sides
- Minimum 16x16px
- Do not change the color
- Do not write the word Facebook next to the logo
- Do not just use the ‘f’, you must use the full logo
- Do not modify the logo, do not add an outline.
YouTube:
www.youtube.com/howyoutubeworks/resources/brand-resources/#logos-icons-and-colors

- The ‘Logo’ contains the word ‘YouTube’ while the Icon does not.
- The free space must be equal or greater than the triangle in the logo
- Must link to a youtube channel
- Supposedly requires special approval for any and all usage
- Youtube provides a circular version if you download the ‘Icon’ not ‘Logo’ (Full color icon/social/red/youtube_social_circle_red.png)
- Minimum height 20px (=width 28px)
- (#FF0000/#FFFFFF/#282828)